Why in some pictures, the units' models and portraits look different? Kind of similar to Disciples I?

[Salyn]

There are screenshots of Disciples II which in combat screen the art of units look much different than it's been.

[QWEEDDY2]

Placeholder pics initiaaly from alpha version. Initially Disciples 2 looks same worst as Disciples 1, but later design changed completely.
There is also some screens of some units models - some looks good. portraits too. They be good in Disciples 1 after all (Lord portraits! mmm...)

[Talis Cat]

They kept the models :
https://drive.google.com/file/d/14aOOmJjMlM6E7UToASw0eA1v_BKilPnD/view?usp=sharing
But not the art :
https://drive.google.com/file/d/1B2kdygeVkvP9sTDiO6LTWB1mOtXHSCVg/view?usp=sharing

I wished they had kept this one :
https://drive.google.com/file/d/1LOoSGpomIooLC3v3KDSArtAJmsEShGtT/view?usp=sharing
Not sure if it was Archangel or empire guardian.

[QWEEDDY2]

There is differ builds according to screens. With, without models. And at same time with differ portrait. There clearly "more recent"(*and not) versions with more earliest models - and vise versa.
Since we only have some screen (video with just screen show case) - we cant be sure what exactly build be early\late and if anyone order in that screens.
Perhaps the put models separably just to make some screens. Some devs team do that before make screen, some - not.

Not every artwork goodies include in GOG releases. Some are include in Steam version of D1. From Gold re-edition CD. 2 Gold CD - more artworks. And there is some more from of.site for D1 and for D2.
I collect a little bit more than on GOG here

but that still not all. In case if you dont have D1 on Steam (or CD Gold) or dont want install it - you can get two bink video in exe files with a lot of early screens showed.
Here goodies not included in GOG but taken from Steam and CDs
http://disk.yandex.ru/d/ey3ytphZ69WbzA
Web-only content not present. Some fan-site kits maybe (there is one for D1 for sure, check mobygames to direct link to Internet Web Archive of D1 site).

[Talis Cat]

In fact i think i got those screenshot from strategy first forum when Disciples 2 was in progress. Sadly i didn't keep data from then :( It was long time ago, no USB key and i wasn't going to burn a CD for this ...
Not sure, though, what with the gamespot logo. But it's definitely the version we had at the time.