What is the difference?

Co-workers are all of those people you work with. Some are on the same level as you, some higher, some lower. You all work at the same place though so you are co-workers.

Colleagues are those people that are your occupational peers (equal level of position and responsibility). Two high school teachers at the same school are coworkers and colleagues. The principal is also their coworker but not their colleague. The principals colleagues are other school principals.

The dictionary tells us that colleagues share class or profession whereas coworkers simply “works with another…”

Via Yahoo answers

A little bit but now you know it,