Strength / Weight Training

I’m sure you’d get £22’s worth of use out of them. If they break you know to upgrade. Impossible to know, but £100 is a fair whack for a pair of dumbbells.

Those more expensive ones have a nicer bearing set in, the cheaper ones are are either lose ball or a cheap ball and cage - they'll rattle around a bit more.
I'd also expect the knurling to be nicer in the rival strength, the cheap ones may be uneven, or have lightly sharp edges... (nothing a quick file won't fix) and lastly the chroming on the sleeve might chip off easier, or even arrive already chipped. Not that I have first hand experience from either sellers but I've sold very similar products before.
Weight limit won't be a problem on either. That being said, if you're not going heavy why are you choosing such a big format? I find the Olympic dB handles to be pretty bulky to start and if you're using tri-grip plates you end up with a massive dumbbell?