So here's the thing, EB-2 requires higher qualifications (advanced degree or exceptional ability) but has shorter wait times. If eligible, EB-3 to EB-2 “upgrade” (EB-3 to EB-2 porting) might speed up processing. That's pretty much all there is to it.

EB-2 is actually on a higher level than EB-3. So basically stricter but with the benefit of shorter processing times.