The first and most obvious difference is height, and sculpting style. Whilst the Platoon 20 figures are '1:76th'. with a 'wargames' chunky build, the Under fire figures are 1/72nd scale, with a realistic build. The details are very cleanly sculpted, and more 'inscale' /less pronounced than the Platoon 20 equivalents. The weapons in particular are very fine, and I have slight concern over how robust they will be.
The quality of the castings is very good - they have minimal mould lines, and no flash/metal fluff anywhere.
Overall, I'm very impressed - certainly if I was doing modern Africa in 20mm rather than 28mm, these guys would be very strong contenders. As it is, they aren't going to be suitable for my planned use as Anti-Soviet partisans/NATO stay-behind forces.
John (he of cracking African scenery fame) was talking about this range the other day - I'll probably pass one onto him to see what he thinks of them 'in the flesh', and if he gets around to painting to it I'll post some pics up so folks can see how they look. The other I'll keep hold of for use in other size comparison pictures...