A few things come to mind as differences:
The Fritz is a fuller sound particularly given the lower end extension down to 37Hz. They are rear ported. It’s a more balanced speaker wrt its flat response curve. It does not accentuate any particular frequency. It is also a very smooth speaker that is well integrated (tweeter and mid/bass driver). It uses a series crossover which helps with both the driver integration and the flat impedance curve. They play everything well.
The Falcon Q7s have a low end extension to maybe 60Hz. They are a sealed box design which makes what bass they do play a bit tighter. They are brighter and do have a bump in the midrange of the response curve. Mine have the Gold Badge crossover which smooths out the edginess in the high frequencies. They are very good for small space near field listening, particularly for vocals, jazz, etc.
I have a couple of subs in my system so I don’t really notice any lack of low frequency response from either speaker.
Both speakers have excellent soundstage, imaging, and transient response. If you have a broad range of musical tastes I think the Fritz would be a better fit, but I’ve played every kind of music out of the Falcons and they’ve done well with it all.
The Fritz will play much louder but the Falcons aren’t really designed to be played at concert levels. That said the Falcons will happily play at 75-80 db all day which is louder than I usually listen. If you like the sound of the Grahams you will like the Q7. The Q7 is a kit, though you can have Falcon pre assemble it, which is what I did. It’s also half the price of the LS3/5a. I would get the Gold Badge crossover as well. One last thing, the Q7 is basically an LS3/5a in a slightly larger cabinet. Here is a link to a review
https://www.stereonet.com/uk/reviews/falcon-acoustics-q7-loudspeaker-kit-review