They are the same nic strength, 24mg. And the VG/PG is 20/80 on both; they're from the same company, Gourmet Vapor. I've never mixed anything before so would it be best to put 2 drops of RY4 in a carto and then 1 drop of carmel and then 2 more drops of RY4 and keep changing it up until I get what I like, and then put the mixture that I like in a seperate bottle? The bottles are little plastic dropper bottles. Can I pop the little plastic dropper tip off? Also, I have a carto that is almost full of RY4, if I put a few drops of the Carmel in it, with it mix good enough?