Fòram na Gàidhlig

Is there a difference between "oisean" and "còrnair"?
Or do both apply to a corner, whether a convex or concave?

I guess the second one is just Gaelic spelling for an English word. It also has the meaning "wrapper" though.

I've just noticed a direct personal comment from Colin Mark in his dictionary, under "còrnair":

"there are at least two good Gaelic words for corner – I don’t see the need for this one"

I hadn't seen the other meaning of "wrapper"---I would have used paisg or còmhdach.