supporter vs upgrades

Hello,
I am new to wordpress and i successfully installed wp mu. I need a plugin that can enable me define storage limit and templates, and so for my users. I tried to install the upgrades plugin, it is installed properly and all the files are stored in the indicated directories...but nothing shows up in the admin area, i mean no plugin appears in the list....
The alternative for me was to try to play around with the Supporters plugin. But i want to know what is the real difference between them ( supporter plugin and upgrades )? Which one should i concentrate on ?
Thanks in advance
Yaz