Both companies are very aware of their intended audiences and customers.
Line6 caters to the typical “buy a pedal and turn a knob for perfection” consumers, who don’t dive in and tweak at component levels, you know, the person that has multiple distortion and fuzz, echo and flanger and chorus, because they don’t know they can make a minor change to one and get the sound of the next.
Fractal, on the other hand, is for the person who will tweak components, maybe not themselves but will take it to their technician and discuss what is needed to fine-tune the sound. They target players who want a very realistic sound and behavior and will put in the time to get it.
I started with Line6 many years ago, way before the Helix line, and followed their technology through the biggest Pods, the amps, into the Helix Floor, sold it all, jumped to the AX8, switched back to my tube amps and (small) pedalboard, then tried a Helix Stomp, didn’t like it, switched to the Floor again, didn’t like it, again, and then, because the FM3 had been announced, got on the waitlist.
I have followed modelers and modeling a long time and the AX8 showed me how close Fractal was to being able to replicate 99% of what makes a great boutique or classic amp stand out. I knew the Axe-FX III was the state of the art and wanted to see what improvements the Ares software brought. And the FM3 blew me away, so much so that I bought a FX3 also, just for my at-home and always connected rig for silent practicing and recording (an important consideration at our house), and the FM3 with a FC6 is for when we can finally play out again.
The Fractal units are so good I sold my smaller pedal board and am selling my biggest boutique amp, because I don’t see a need for them. The other amps, also high-end boutiques, are possibly on the chopping block, along with the pedalboard.
The Helix sound was OK, as was its touch response and build, but Fractal has so much more depth and control, feel and response, and is so much more amp-like. The Helix didn’t inspire me, nor did it convince me I could replace my analog gear.
And that’s what I think the difference is.