Bathys is physically smaller. Lighter (with more plastic in the build). Of course more portable.

Sound wise they’re similar, but I find Bathys does have a slight veil (which can be tweaked in EQ). Bass is more pronounced on Radiance. Mids are similar, but Bathys has a dip at 1k (which is also fixed in the EQ in the app). They’re both the Focal house sound.

Radiance has more stage and separation. Detail is similar.

I prefer the Radiance though at the house as the differences are enough for me to notice and enjoy. The Bathys are definitely my portable choice and as well are great. I just wish I had more adjustment options as I’m maxed out on the yokes.

I’m still learning to identify differences in timbre and separation and resolution. So I hope that helps.