I agree that when the square LCD screen is fully viewable with a light colored image (like in that Yoga picture on the watch) that it looks like you say (it was also the first thing I noticed). I don't own an Apple Watch so I went to their website to see if their watch also looked the same. I couldn't actually find any image on Apple's website that showed this - they carefully make sure to only show black backgrounds so you don't notice it. I'm guessing you might not have made your comment if FitBit didn't show the watch face with that Yoga picture.
I'm not an Apple Watch owner either, so no dog in the fight, but one of my kids has one and it definitely has more active screen than the Fitbit appears to have.