On sharing images

When sharing images what’s the difference between a thumbnail and a preview? Also what is the BBCode and the difference between the full-size and thumbnailed BBCode?

The comments here are Textile-based, not BBCode. The p, t, and s suffices are for embedding an image (listed in decreasing order of size)

@PUBLIQclopAccountant  
I see.

As a visual example for anyone else reading this thread, different-sized previews of >>2371280 (in increasing size this time, STP order)