jkno would be the authority on this, but for those weighing "waiting for the ROTJ version" or not, here's a comp pic of the ROTJ vs Mando scout versions. Me... I'm getting both.
The Mando and ROTJ scouts would obviously be interchangable for most people, the crisp white vs dusty yellow look being the main visual difference. But there are quite a few minor outfit differences. I've left out a few in these pics, like the Mando's more squared/sharp edged knee armor, the stomach-area pouches being more boxy in ROTJ, and minor differences to the grenade on the back.
This is ROTJ screencap, Mando screencap and HT figure:
Most obvious difference is so-called "saggy" chest armor (way taller than the ROTJ version) and the armor neckline on the back is more like a tank top in Mando and squared, not round. The peak above eye lens is flatter in Mando (more so on the figure than the costume) but more curved in ROTJ, and in Mando the shoulder armor is more straight and tube like and longer vs curved and smaller in ROTJ, the bicep armor is a somewhat different shape, buckle more square, and hip armor more boxy and fatter, and the airsccop backpack has differences.
This is ROTJ on left, Mando on right:
