There are two things :-
1) You always get a PGWP post studies so they know that once you have Canadian education, you'd work and help their economy
2) SOP should state, the program you've chosen, the reason of choosing that program and it should match with your previous studies. How that program would help you and any discrepancies that you think is important for visa officer to know.
Not mentioning this, wouldn't affect your application by much.
Goodluck !