Most of the Merseytravel Christmas Day routes are unique to the day.
12A, as you say is similar to Arrivas 12/13 services but extends to Huyton when the core services don't.
21A runs from Liverpool One (other days the Kirkby services start from Queens Square) and plods around more of the estates in Kirkby.
62A, as you said.
201 doesn't serve Queens Square normally, it only runs to/from Royal Liverpool Hopsital.
They’re the former routes from the early 00’s/late 90’s that have never changed
12A is the former Liverbus/MTL/Arriva 212
21A is the former MTL/GTL 1.
62A is the former MTL/GTL 92
H1 is the former 118
H2/3 is former 194/195