When I do the butterfly stretch, I can get my feet fairly close to my groin and my knees fairly close to the ground. If I grab my toes I can easily pull my knees to the ground. I sit in this position a lot and find it comfortable. That said, I can barely lean forward, and I don't know what's stopping me.
When I do the pancake, I can get quite low. With back straight I can touch my elbows down and if I arch I can easily get my forehead to the floor. When I do this, though, I feel the stretch in my inner thigh quite strongly. I feel almost nothing in the butterfly, neither sitting nor leaning forward. If I wait long enough I feel a slight sensation in the groin area, but I think that's just muscle fatigue from pulling the knees down.
So my question, what changes when one leans forward in butterfly vs the pancake? Why does one feel like a good stretch while the other feels almost nothing? And is there any supplementary exercises or material I could do to help? Thanks.

