console.log() on setTimeout() JS [duplicate]

Question

can someone help me understanding why this code:

for (var i =0; i < 2; i++) {
  setTimeout(console.log(i), 0);
}
console.log("aaa");

Will write:

0
1
aaa

But that code:

for (var i =0; i < 2; i++) {
  setTimeout(function(){console.log(i)}, 0);
}
console.log("aaa");

Will wirte that:

aaa
2
2

Note that I understand how the second vers. work, I don't get why the first one make it differnt.

Thanks!