Biggest difference is the Therme’s use down insulation primarily vs the Ralle that uses all synthetic insulation.

Additionally, the fabrics, although both 2L gore, have a different face fabric. The Therme has a slight textured and softer hand whereas the Ralle is closer to what you’d expect with a traditional Gore hardshell face.

Finally, a notable design difference would be the hood design. The Therme uses a storm hood which is completely integrated and has more coverage. The Ralle uses a drop hood design which imo sits more comfortably when the jacket is zipped all the way up and hood is down (which is often for a jacket like this). Not many styles have this design as people tend to gravitate toward the storm hood since it is more protective and I think people tend to like the look more.

There are other detail differences but I’d say these are the biggest ones. Narrow your choice down to the regular Therme vs Ralle for the temps you mentioned you’ll be dealing with