What's the difference between fabric gym belts and regular ones?

Fabric ones fasten with velcro and are way more comfortable for long workouts, while traditional leather belts are stiffer and are mostly used for heavy weightlifting where you need maximum stability.

Don't be fooled into thinking the velcro on fabric belts is less durable, because it holds up great if you take care of it a bit! What people don't mention as much is that the fabric breathes way better during long sessions, so if you sweat a lot or train in summer you don't end up with that sticky feeling you get from leather. They're ideal if you're after comfort without sacrificing support, though obviously for maximal strength lifts the traditional rigid belt is still more stable.