A cartridge aka cart sticks on or in an atomizer - the atomizer can break or need cleaning etc, but a cart can be restuffed and used over over - however carts generally suck, need frequent topping off, can dump their juice, etc
A cartomizer is a disposable combined cart with internal atomizer - all one piece that screws onto the batteries. Great for your favorite flavors, each flavor has its own atomizer. They hold more juice than a cart, generally need juice added less often, provide a more consistent vaping experience. I can get a week or more use out of a standard stuffing carto like Boge. Some people try to clean and dry them with mixed results and you cannot restuff them. There are also more exotic cartos like reservoir styles and clear reservoir ones that crack and fall apart (but the new CE3 ones may be better). Slim 510 would use standard resistance (2.5 to 3 ohms), and fat batteries like Ego and Ego-T can use standard or the hotter LR ones (LR also uses battery charge up faster). I think thin juices work best - I use 80PG/20VG or less VG. No problem using them on Ego-T because a cartomizer replaces both the atomizer and the tank.
BTW - orange professional flavoring (with no sweetener, such as you should have used for your eliquid) - citrus, nut and certain spice flavors are frequently oil based and difficult to use for making eliquid and I think need so extra step with alcohol?? - dunno - read the DIY section guide. And oil may also gunk up attys quicker.