1. Both files are SFX-ZIP, not pure zip, so can be renamed to .EXE (winrar easily handles it though).
2. They are identical, except FAQs
and .ex_ files (ugh, it makes it less special.

, that have different download addresses inside (both dead) and .inf file that installs it by different names. Part 2 have _much_ more resources though.
3.
Funny enough, it really makes different exes! (Resources are still identical). Incredible, eh? %) Part 2 can load puzzle pack from part 1 though, that makes part 1 totally obsolete in result.
Otherwise it works for me.