Use lifting straps instead of a lifting belt when the limiting problem is grip, not torso bracing. Straps connect the hand more securely to a bar, handle, or dumbbell during pulling work. A belt gives the trunk a surface to brace against during heavy loaded lifts.
The distinction matters because both accessories can appear in the same gym bag while solving different problems. Straps can help when the target muscles still have work to do but the hands are failing. A belt is more relevant when the lift demands a stronger, more consistent brace.