Um.... Ok.... here goes.
510 atties fit 510/Riva-510/Ego
batteries. 901 Atties fit Riva-901/901
batteries.
510 atties are available from 2 different manufacturers... EM, and Joye (OEM). 901s are from EM, and SLB (OEM).
Both are available in multiple resistances. The lower the resistance, the hotter the coil gets, and the warmer the vapor.
LR atties (≈1.5-1.7Ω) are designed for 440mAh+
batteries only. 3.7v. (EGO/RIVA)
Standard atties (≈2.0-3.3) are designed for mini/ super mini style batteries (510/901), as well as anything larger like the ego/riva.
HV atties (4Ω+) are designed for High Voltage devices (4.5v or higher). These devices are generally called Mods. But 5v Passthu's are also available.
EGO atties, are big and fat like EGO/Riva batteries. either conical, or cylindrical. This includes Ego XL, Ego XL LR, and Ego-T style atties. The general idea behind these, is they negate the Ego/Riva cone, and hold more liquid.
I hope that makes sense.
We will be adding some videos to the website in the coming weeks to clarify many of these issues.