'(Note: This article in various forms has been published by different magazines in the past like Yoga International and Hinduism Today, and been put on various websites.)
Yoga and Buddhism are sister traditions which evolved in the same spiritual culture of ancient India. They use many of the same terms and follow many of the same principles and practices. For this reason it is not surprising that many of us born in the West, particularly after an initial exposure, are apt to regard Yoga and Buddhist teachings as almost identical.
We may want to combine their teachings or practices accordingly, as if there were no real differences between them. The differences that have existed between the two systems historically, which have kept them apart as separate traditions, are less obvious to us in the West than are their commonalities. Or those who study one of these traditions may be inclined to see the other as a borrowing from it. Those who study Buddhism may find so much similarity in Yoga that they suspect a strong Buddhist influence on Yoga. Those who study Yoga may find so much similarity in Buddhism that they see a strong yogic influence on Buddhism.
This article is by David Frawley