What
@Wildcatsare1 said about the comparison to you is pretty spot on in my opinion.
Listening to HD800 and Focal Clear out of the Hugo 2-
Female voices in the song "say something loving" by the XX- sounds like they have more body to them on the Clears the HD800. The HD800 comes off a little more sibilant with "s" sounding words.
The HD800 sounds a little more frail or thin in general to the Clears.
HD800 still has wider sound staging though, if that is important to someone.
Transient speed goes to the Clear. This was best illustrated for me on the song "Mediterranean Sundance/Rio Ancho (live)" at 6:09. The finger plucking of the guitar is wicked fast and each note is very "clear" for back of a better word with the Clear. The HD800 is still no slouch (we all know that) but it was more fleshed out with the Clear. By the way I highly recommending listening to that whole track. It's my favorite right now!
I tried volume matching to the best of my ability. some tracks I got up to light purple with the HD800 at a maximum. Majority of times I stayed around light blue and light green for Hd800 and Clear respectively.