Yes, there's a difference between spanking for sexual fantasy play and "domestic discipline." The latter is a lifestyle, wherein one partner punishes the other for "bad behavior," usually through spanking. IMO, it's unhealthy and demeaning. Spanking as a sexual game or way of arousing a partner is completely different.

CrystalRose, good point on the sex therapist title...but sexual surrogates often do have sex with their patients/clients.