Yes there is a difference. Direct inhaling is when you draw the vapor directly into your lungs instead of (or in adddition to) drawing a mouthful of vapor, then inhaling it. With a little patience and practice, you can learn to get all the throat hit you could ever want, and produce reDONKulous clouds of vapor like the guys do in the videos.
Tailpiping is when you use an atty without a cartridge or a mouthpiece, and just suck on the end. 801-style atomizers are longer and more suited to tailpiping, but people do it with other types of atomizers as well.
Direct-dripping is when you do not use the cartridge filler to wick juice to the atty, you just drip a drop or 2 directly onto the "bridge" of the atomizer whenever it needs it. It sounds like it would be more trouble than it's worth, but for me it's the other way around. Filling carts is much more trouble, for me. There's a link in my signature below that will take you to an introductory guide.