This is seriously funny... According to the yinbiao, there is some subtle difference...

"Principle" and "Principal" are one of the homophones. homophone is a word that is pronounced the same as another word but differs in meaning; therefore the answer to your question is there is no difference in pronunciation.

There is absolutely no difference in pronunciation. If I told anybody vocally too spell either "principle" or "principal", I would either have to give the definition the one I was talking about or say "principle as opposed to princi-PAL", deliberatly mis-pronouncing the second one to make it clear which one I was meant.