dear ankit,

the on campus placement is generally organised by the colleges or the universities.In this type of of campus placement the placement cell of the respective college is responsible for organising campus placement .Here is a limited competition because only the students belongs to the college can eligible for this type of campus placement .No of candidate are less as compared to off campus placement

on other hand in off campus placement your respective college doesn't play any role.In this case you have to apply or participate directly  placement organised by MNCs and sometimes by different colleges .anyone full filling the eligibility criteria form any college can eligible for it.Here you have to face more competition as compared to on campus placement because number of candidate is more as compared to on campus placement .

Hey,yes there is difference between off campus placement and in campus placement.in campus placement majority consider the cgpa of all four years and other out placement considers the exam score of conducts their own examination.this is major difference.