Incorrect

There is ONLY ONE emulator, and that is Microsoft's. There are a couple of translations and several packages, but it's always the same emulator.
And, of course - there are limitations that we have established empirically.
In the case of iGO, they refer to the amount of content (literally, the size of maps and addons) and number of ux files (or skin plugins, zip files...).

You can read about it in the appropriate topic, there is no need to write here.