Some suppliers will take the regular 510 or 901 and brand it with a fancy name. It will come with logos on them or maybe custom packaging. They might then mark it up and have a higher price. But when it comes down to it, a 510 is a 510. You may want to read Chris's blog about Janty and Joye. It might make things a bit more clear. Ecig Guru Blog
Looking at your title for this thread you mention the Joker. The Joker is a whole different type of ecig. Models like the Joker, Silver Bullet, Indulgence and the Chuck, (to name a few) are what we call mods. These e-cig modifications are built for longer battery life and more power. The batteries used in these will extend the time between charging. A regular 510 battery lasts a couple hours and a mod will last up to 8 hours or maybe longer before having to be re-charged.
The other purpose of these high dollar mods is the voltage. The Joker for example is a 5v mod. Other mods like the Chuck can either be 3.7 or work at 6v. This depends on the battery combination that you choose to use. The regular 510 battery performs at 3.7 volts. The higher the voltage the more power to the atomizer, which means more vapor. Most of these mods are hand made by manufacturers in the US. Except for the Indulgence, I think that is made in China.
I hope this helps, I tried to make it as simple as possible.