This is interesting. I didn't know these terms at all so I looked them up, and it seems that there is a difference between the two. Here is the link,
Blending Scissors and Thinning Shears:
QUOTE
Blenders have teeth on one blade only for finishing and blending. Thinners have teeth on both blades for cutting closer to the scalp or fine texturing.
I don't know if I'll ever use the terms again but at least I learned something this morning. Thanks.