Hi
The main difference between a GBIC and a MiniGBIC is , the size !!!
A mini-GBIC takes about half the size of a "normal" GBIC
-> You can then have more ports on a single blade
The purpose af GBICs ( and MiniGBICs ) is to be able to mix SX,LX, and LH port on a single blade/switch or migrating from SX to LX for instance, without changing the blade/switch
HTH
Fred