VV is Variable voltage, meaning you can choose how harsh or light you want the vapor produced to be.
Mod is something like a box mod or such that usually has a spot for a carto or some even have a spot to place a Bottle of juice directly in the unit and usually use disposable batteries, the rap they get is they aren't as sexxy however they come from private vendors who are usually good people and people who have made the switch themselves.
A 510 and 808 looks alot like a cigarette just a bit longer, think 100s or Black and Milds
An Ego to me is more of a metalic cigar design however you do not have a charging case that you can get with 808's and 510's and IMO is not better at producing Vapor than an 808.
Bloogplanet.com has IMO the best 808 design and vapor production, smokessimage.com has the same design and cartomizers for cheaper, also a kit will come with IMO the most reliable charging case available.
I still suggest trying to find a variable voltage to figure out your sweetspot and using it for your home vape, and getting something like a Bloog or Volt from Smokelessimage.com for your on the go.
At least with a Bloog you can get 36mg nicotine for your carts, however the flavor selection is slim, But they have one of the better Menthols IMO.
Choice is yours, just shuffle through and make sure you get the right unit the first time.