Hello Aspirant,

If the campus drive is off campus then the student from all across the country can give the exam and interview as well, whereas if the campus drive is on campus the only the students who belongs to the institution that provided the campus drive will only be able to give the exam and interview as well.

On campus drive are provided by the Institution or University for the student who are enrolled into the Institution or University. On campus drive are the opportunity that is only provided to the Institute or University student, but Off Campus drive give this opportunity for every student belonging to different Institute or University.

I hope this will help you.

All the best for your bright future ahead.

No the students of the college are only eligible for campus placement but not other students. Also in campus placement there can be different eligibilities for different companies. Also some placements can  be open for all the branches and some may be for specific branches. But outsider students aren't allowed in campus placement.

I hope this gives you a insight. All the very best for your future endeavors!