Welcome!
The alphabet soup can be a little confusing at times. I know I was lost at the start, and gradually got into the swing of things!
I'm sure someone will come on and give you a link to the extensive list. Sorry I don't have it.
As a starter and to answer the one you specifially asked about ...
OBW = One Block Wonder
and often seen with OBW is reference to
4PP = Four Patch Posey
SAW = Stack and Whack
And one that had me stifled for awhile
LQS = Local Quilt Shop
As you have others, don't hesitate to ask!