They are completely different shows. HEA is the best nighttime show in all of WDW IMHO. Crowds will most likely be large, however, since they are sandwiching HEA in between the party nights and HEA nights are few and far between.
Unfortunately, as of now, Holiday Wishes is only scheduled on
MVMCP nights. HEA is scheduled during Christmas week until Dec. 30 and 31 when they will do Fantasy in the Sky for NYE.