1. The clock GMT function can show 2 time zones, whereas the watch GMT can read three at the same time.

2. Regarding values. Interesting that the Super 24 has a higher value than the normal 12H, apparently due to it's rarity.
Whereas, in my experience, the Mastertime 24, although rarer than the 12H is more difficult to sell and seems to have a lower value.

BTW. I am aware of Jeff's comments about scarcity of some Super Autavia parts. This one must be an ideal candidate.
I also read somewhere their value as paperweights if they break.

Johnswatch Dashclocks always appear to be advertised at first for double their value. But then, he only needs one buyer!