Different models usually have different threads and cannot use each other's stuff unless there is an adapter available. So 510, DSE901, DSE801, KR808D-1, RN4081, etc cannot use each other's stuff without an adapter. And if you get an unpopular model, then there won't be any adapters.
Then there are the ohms of the atomizers. Standard resistance atomizers and cartomizers (usually in the high 2's or very low 3's in ohms) can be used on slim batteries. Slim ecig batteries usually have electronics that are only capable of preventing over-discharge damage from standard resistance atomizers.
Lower resistance atomizers (and cartomizers) run hotter and use battery charge faster and could draw power too fast for the little electronic protection circuits in the slim batteries to deal with. So they can damage a slim battery. If you want those hotter atomizers and cartomizers then you need to use batteries that are 450mah or larger (not slim ecigs). Joye Ego, Riva 510, etc can use LR stuff. But even then, some people don't know if it's safe to go much below 2 ohms on those. Some people will only go really low resistance (like mid 1's in ohms) on mods which use industrial batteries that come out for charging the way a flashlight's batteries come out.
That is all a simplification and only relevant for more common voltage ecigs like 3.2-3.7v. For high voltage ecigs like 5v mods, high 2's and very low 3's atomizers are their "low resistance" and there are special HV or HR atomizers in the mid 3's which are their standard.
There are equations using battery voltage and ohms resistance of the atomizer to determine how much power is being used and how much wattage heat is being produced.