The musical phenomenon of the 2010s vs the musical phenomenon of the 2020s
(Granted, the 2020s are only halfway through and something bigger could come out, but so far, KPDH solos.)
Thinking on it, there's obviously a formula that seems to resonate with audiences. Let's explore that, followed by their differences and how they manage to differentiate themselves from each other to tell unique narratives. I'm gonna try to mainly stick with "Frozen" since, despite the sequel breaking more records, hasn't stayed in the public conscious as much as the first.
Marketing titles--Starting off, the titles of the films were done in a smart way; "Frozen" was done due to Pixar influences and concern that male audiences give the film a chance if it had the title "The Snow Queen." Meanwhile, "Kpop Demon Hunters" is pretty direct, explaining the concept, which is super interesting, given that Kpop is huge in the western world, and the concept of demon hunters is also a popular concept. Both films knew how to appeal to an audience and succeeded well, with further positive word of mouth helping them to become even more successful.
Different cultures--While "Frozen" took on new territory by placing a fantasy fairy tale in a kingdom inspired by mid-19th century Scandinavian countries (particularly Norway), KPDH took on modern-day South Korea. While Disney's use of Scandinavian culture was moreso for aesthetics and thematics (with Norway in particular being singled out for the more dramatic landscape), KPDH being a contemporary story thus relied more on accuracy with Korean idol culture as well as the country's unique folklore, and thus feels more obviously weaved into the narrative. In any case, both films offer a unique setting, in contrast to the usual medieval, vaguely European influences done for fantasy musicals.
(Note: the picture of Kristoff I used was from "Olaf's Frozen Adventure," but I felt it illustrated the point well.)
The ostracized girl who learns to love herself--It's fun to see how you can tell the same story in multiple ways, right? That's what makes a story timeless. Elsa learning to love a part of herself that she was always told to hide is identical to Rumi's own journey, which she was always to was wrong and an abomination. The girls finish their arcs in a better mental and emotional state than before when they learn how to be their true self honestly and openly. It's a story that really resonates with people who may not feel seen or respected for their heritage, status, gender, condition, etc, and both "Frozen" and KPDH manage to show it in an entertaining and raw way. They also create a grey line on what makes someone a monster.
Different musical styles--This is probably the biggest difference between the two, as far as the average person would be concerned. "Frozen" focuses on the traditional musical-theatre style of musicals in order to make soaring music that felt timeless. In contrast, KPDH, as the title suggests, was tailored specifically for the radio as Kpop music (which takes a lot of influence from western pop and hip-hop music, thus helping it get an international appeal), grabbing people involved in the industry to help the authenticity of the music. With both films, they managed to gain international success and break records, though both surprised people for different ways; "Frozen" dethroned Beyonce's self-titled album on the Billboard Hot 100 as well as becoming the most-successful animated film soundtrack since the 90s. Meanwhile, KPDH reached similar success with a no. 1 soundtrack in multiple countries, with Spotify even revealing that the Huntr/x and Saja Boys were the most successful Kpop artists on their radio, dethroning BTS and Blackpink. These differences in styles also suit the story; since KDPH circles around pop artists, the music has to reflect it, and since "Frozen" is more theatrical, the music accommodates for it. In both cases, audiences loved it.
The love that doesn't work out--Granted, the circumstances are wildly different: Anna discovers Hans didn't truly love her and simply wanted to use her for her proximity to the throne, while Jinu and Rumi have legitimate feelings for each other but it's hampered by Jinu's status as a demon, his own insecurities, and the main antagonist of the film pressuring him to carry out his will. That said, my general point is the same; the film presents a couple that is supposed to seem sweet and perfect for each other, only for it to end in a disappointing way. While the love of Anna and Hans was a deconstruction of the traditional Disney romance of previous decades, KPDH instead takes influence from K-dramas to pull at the heartstrings. Both are romances you're sad to see fall apart, though the reasons are probably different (Hans' switch-up feeling abrupt and Jinu's redemption leading to him no longer being with Rumi, at least in an explicit way).
Different visual styles--On one hand, you have "Frozen," which follows the trend of 3D animation and using it's advantages in realism to make the environment (clothes, hair, and most importantly, Elsa's powers over ice and snow) to feel immersive and mesmerizing to look at. On the other, you have KPDH, which sees Sony following their own trend of hybrid animation, blending western 3D animation and eastern 2D animation. Both films thus had an aesthetic that could immediately entice audiences.
The relatable girls--It's interesting to see how animation has portrayed female leads over the years depending on how women are viewed in society and how female writers and directors make them. Anna is dorky and goofier than the usual Disney protagonist, especially one originally intended to join the official Disney Princess line, and the Huntr/x are no different for their film. In contrast to the typical archetype of female leads as serious or delicate, the females in "Frozen" and KPDH are much more comedic and down-to-Earth, making it easier for people to empathize with them, which makes them A LOT easier to market.
Different focuses--Some people may disagree on this, and KPDH 2 could prove me wrong on this, but while Rumi and Elsa had similar themes, Rumi, Mira, and Zoey came to their epiphanies a lot quicker. While Elsa learned not to fear her powers in the first film, she didn't learn to really appreciate herself as a gift and keep questioning her existence until the sequel, and Anna similarly isn't able to overcome her codependency on Elsa (brought on from years of isolation and the romantic trauma that is Hans) until then as well. KPDH could definitely continue the journey of understanding yourself in the sequel, but as of right now, they did it faster. Along with this, while the girls' friendship was central, Rumi was the one with the main arc, not Zoey or Mira. In contrast, both "Frozen" films focus on Anna and Elsa having storylines that play off of each other. On top of this, the antagonists of "Frozen" films have smaller roles, with Hans being a twist villain at the end of the film and the Duke of Weselton being a temporary problem, and King Runeard having started a problem decades ago that's felt now, but he's no longer alive to serve as an active antagonist, his granddaughters mainly fighting his legacy. In contrast, Gwi-Ma is a present and constantly scheming antagonist for Huntr/x that they have to defeat, creating a more clear line of "good" and "bad" from the get-go (though it does get complicated with time, Gwi-Ma remains the main threat).
Sisterhood--At the end of the day, the relationship between women is an important cornerstone of both stories. Rumi learns to trust and confide in her sister-like coworkers/part-time demon hunters/full-time friends, while Elsa and Anna repair a relationship that had been damaged since childhood. Having positive relationships with those close to you (especially the prioritization of same-sex platonic relationships over opposite-sex romantic ones) is something that a lot of people can enjoy, particularly as this topic wasn't covered as much in the past for animation, especially for female leads.
Curious to see what the musical phenomenon of the 2030s will be, or if there's gonna be one in the 2020s that overcomes KPDH (doubtful, but still). NGL, as someone who finds male-led musicals underrated (especially if we just look at animation), I'm hoping the next one has a male lead.