As I understand it having attended a lecture from Dr Watkins at the National
Honey Show last November,  the chemical is the same (fluvalinate) in both
Apistan and Bayvarol but the method of delivery is subtly different as the
different plastic strips used do not allow the fluvalinate molecules to arrive
at the surface at the same rate.
 My apologies to Dr Watkins if I have misunderstood and also for trying to
encompass part of a long and fascinating lecture in a single sentence.
Chris Slade