no probs with the qns, just ans with what I know
Epoxy putty and Tamiya putty both different thing, so different uses
Epoxy putty consists of 2 sticks, 1 stick is resin, other stick is hardener. Cut and mix equal amount of both, no need thinner. Something like dough, apply to area. Takes quite long to harden, I usually leave it for about 6 hours before doing anything to it. Once harden, its very hard, still sandable but not so easy. Epoxy is good for shaping and sculpting stuff since u can play with the shape as it is dough-like.
Tamiya putty is paste-like, squeeze out of tube can use le. Good for seamlines and small gaps. Dries fast too. Since it is paste-like, it cannot be shaped to your desired shape.
So in my opinion, if ur intention is to clear seamlines and small gaps, tamiya putty works better. If you are scratch building something, use epoxy putty cause u can have more control over its shape.
What I do for HG kits with huge holes (like those that I filled in the last pic), fill with epoxy putty first. When it has hardened, sand/slice of excess. If any small gaps/holes spotted, fill with tamiya putty.
Hope this helps!