Despite the same name, they are two entirely different models. Modern Vapor's 902 is somewhat similar to but incompatible with the DSE901 mini (the typical three-component
device).
CigEasy's 902 is simply what they call the manual battery version of the Kr8 two-component cartomizer (integrated cartridge and atomizer)
device. It is compatible with other Kr8 parts (e.g., cartomizers) and accessories (and with DSE901 atomizers BTW).
Somehow I doubt that they consulted with each other prior to naming their products.
If you are a Mac rather than a PC, Modern Vapor's model may be a good choice. That is, it is not compatible with any other e-cig model
nor with
any mod (to my knowledge). But, like a Mac, that doesn't mean that it is a bad device. And then attys don't last that long anyway. You can always buy some 510, 801, or 901 attys to go with whatever mod you might want to use in the future.
Otherwise, I recommend to new vapers either the Joye 510 (or more expensive eGO/Tornado using the same atty) or the Kr8. They each have many (different) strengths. They also have PCCs (although not as pretty) and I believe the Kr8 cartomizer holds at least as much e-liquid as the MV 902 cart.