Simple test here, all images taken in Leica SL and given same white balance. Link to all images here, but you will find some comparisons below.
Leica SL 7Artisan 35mm f1.4 at f1.4
Leica SL TTArtisan 35mm f1.4 at f1.4
TTArtisan 35mm f1.4 flare
TTArtisan
Pros
1/2 stop aperture clicks
“Leica look”
Smoother background blur
Seemingly less barrel distortion
Better screw-in hood
Best CA performance in extreme back-lit situations
Cons
More focus breathing
Slightly less refined build
Heavier at 413 grams with hood, no rear lens cap
Same
Sharpness wide-open
7Artisan 35mm f1.4 flare
7Artisans
Pros
Better build
Less focus breathing, lens remains same size while focusing
Tighter build tolerances
Lighter at 376 grams with built-in hood and no lens caps
More contrast in extreme back-lit situations
Cons
Only full stop aperture adjustment
Slightly more CA in extreme back-lit situations
“Busier” out of focus areas
Same
Sharpness wide-open