You have asked about placement, that is why, first I'd like to you tell you that the difference is almost reaching the bare minimal as the two colleges are exactly like each other in terms of teaching and faculty. You can contact a teacher from psit coe when you are in psit and a teacher from psit when you are in psit coe if required.
PSIT and PSIT COE are both the colleges of same level. And they share everything the same be it infrastructure , laws , guidelines , notices etc.
The only thing that is different is their college codes. These two colleges have been differently set to get a larger number of admissions.
So , the placements of both the colleges are also same. There is no measurable difference . Big companies like infosys , tech mahindra , capgemini visit both the campuses for recruitments.
Hope it helps!