Those both match given the string "Blah,Y,X", which
has a substring ending with ",Y", but doesn't itself end with
that sequence. (It isn't completely clear to me what the OP
wanted, though...)
I interpreted it as meaning a ",Y" after the name string. Many others interpreted it as meaning a ",Y" at the end of the line. The OP wasn't clear so I figure I would share my interpretation.