Assuming that this is a simple CSV file, without any fancy embedding of commas in the actual data, you may use awk to do this:
awk -F ',' '$1 != $2' <input.csv
This is a shorthand way of writing
awk 'BEGIN { FS = "," } $1 != $2 { print }' <input.csv
and it sets the input field separator to a comma and prints each line if the first and second field ($1 and $2) are not identical.