In lang=en terms the difference between skag and snag
is that
skag is an alternative spelling of lang=en heroin while
snag is to obtain or pick up (something).
As nouns the difference between skag and snag
is that
skag is alternative form of lang=en while
snag is a stump or base of a branch that has been lopped off; a short branch, or a sharp or rough branch; a knot; a protuberance.
As a verb snag is
to catch or tear (e.g. fabric) upon a rough surface or projection.