Yes forget about them. They are only of use to people doing engineering stuff like I mentioned. For example, they are much more efficient at rendering realtime wireframe views than gamer cards. Not very useful to us to say the least...
Again: depends on what you want to do. Very important difference you need to understand (since people don't feel like looking this up themselves): Realtime rendering: viewport stuff, 60+fps, realtime superfast. This is what games do, this is what the viewport does. Uses realtime shaders, does things like post-processing,…