BlueIceCrew, your explanations made no sense.
OPK - "teleports" enemy player infront of you (only on your screen, on his screen he's still running around somewhere) so you can kill him, that's atleast how Semi OPK works. Full OPK most likely teleports the whole enemy team.
Telekill - teleports you to an enemy so you can kill him (the distance is enough for knife kill) and when you do that, then it switches to next enemy and so on.