There isn't much difference. Perhaps a pang is slightly more guilt.
By the way, I always used the expression "tinge of guilt", not "twinge of guilt", but both seem to be in use according to my online dictionary. A "tinge" is a small amount. A "twinge" is more like a pang, in that it is a pulling action.
I would say "pang of guilt" is the least common of the three, but all are fine.
I hope that helps.