Ignition Coils

I have to buy an Ignition coil for my 90 integra LS. What is the difference between the OEM coil and the Aftermarket ones. The coil by Bosch is like $40 but the OEM coil is $70. Why is there such a price difference? Will the Cheaper one burn out earlier?

OEM is always over priced unless you know someone who works at the dealership. Other than that they are pretty similar, but it has been my experience that OEM parts fir the best and perform the best.