What's the difference between ABEC 3 and 5 rollarblade bearings?

I took the ABEC 5 bearings out of my normal recreational blades and put them in my aggressive inlines that had ABEC 3's in them.they r all oiled great and before i test them i want to know the difference between them.
Update: also i have the abec 5 bearings in only 1 wheel and the other bearings in teh other wheel are the ones they came with