Given a macro test-return-enter bound to some key:
tapKeySeq a b c return return d e f return
delayUntil 2000
tapKeySeq a b c enter enter d e f enter
delayUntil 2000
tapKeySeq d o n e dotAndGreaterThanSign
When I run it, the output shows that return did not produce any output, but enter did actually create line breaks.
I was under the impression that return should also generate line breaks, but it didn't.