What is the difference between passing out and fainting?

Answer 1

there is no difference, "passing out" is simply a new invented slang term, where as "fainting" is the traditional English way of saying.

Answer 2

When you faint, you will wake-up after a few seconds. When you collapse, you may not wake up as quick or at all (unless your saved by professional first aid, eg. CPR).

Answer 3

The main similarity between the two occurrences is a loss of consciousness. A seizure however can be accompanied by violent convulsions and respiratory distress.