ATV stands for All-Terrain Vehicle. They are typically smaller and made for single riders, and seem to just be more for fun. ATVs typically have handlebars, like bikes, whereas UTVs and EVs usually have steering wheels.
UTV stands for Utility Task Vehicle. They are larger, more expensive, and can typically hold several people. They are more for actual work on a farm or park or such. They typically have more safety features than ATVs. They also tend to be slower than ATVs.
EV just stands for Electric Vehicle.- They are powered by electricity, typically several rechargeable batteries. They can be used as either an ATV or UTV’s purposes. The cost varies widely.
This varies from state to state, but you don’t typically need to register your ATV, UTV, or EV to drive it off of a road. On roads, you typically do need a registration.
You do typically usually need a title for the vehicle to drive it at all. This also varies from state to state.
Check your state laws to make sure!