difference

I don't think there is any difference.
These terms simply refers to the physical size of the system - very small.
It has nothing to do with the audio quality of the playback either. Stereo = 2 channels (left + right). And some system includes a sub woofer out for easy setup when connecting a sub-woofer.

2012-07-11 23:22:12 補充：
There is no standard classification for hifi when it comes to size. For professional use, most equipment are 19 inch in width, and height is multiples of 1.75 inch. Because that's the standard PA cabinet size. Mini vs Micro, is just a name .

2012-07-11 23:23:27 補充：
Just like "used car" vs "pre-owned" . Some big boss like their product called mini, and some like micro. So the marketing dept just follow whatever the big boss said.