How do you tell the difference between a honey bee and an African honey bee?

With very great difficulty.

The native African bees are smaller, and build smaller comb cells than the European bee, but when cross-bred with the European bee the offspring are same size as the European bees. They do have slightly shorter wings, but the difference is small, and a statistical analysis of a large number of the bees is needed to tell the difference. The trouble with this also is that the Egyptian bee, present in the southeastern United States, has the same morphology and would be falsely identifed as africanized.

The only definitive test is by DNA analysis.