Linguistically
choking and suffocate can be both transitive and intransitive. "I choked" "He choked me" "He suffocated" "You're gonna suffocate him" "Suffocate" sounds stronger and more formal -- it gives the impression of death. Smother, strangle, and stifle are all just transitive. "Smother" focuses on someone placing an object over someone else's mouth and nose so that they cannot breathe. "...
Semantically
You can choke on something (and people will try to do the Heimlich to save you, hopefully!). Or someone can choke you; that's pretty much the same as strangling. Strangling is putting pressure with something around someone's neck so that they can't breathe. Suffocation is a death by lack of oxygen. You can suffocate in a room filled with smoke or by being in a tiny room and using up ...


choking
prevent (someone) from breathing by constricting or obstructing the throat or depriving of air. 2 have trouble breathing. 3 (often be choked with) fill (a space) so as to hinder movement. 4 make speechless with strong emotionChoke

suffocating</B>
die or cause to die from lack of air or inability to breathe. 2 feel or cause to feel trapped or oppressed.