Belgium is fine. They just count all suspected C19 related deaths. The UK is different. We let doctors in private nursing homes (for example) make that decision.
I guess that depends on who you compare against. Sure they report more of the actual dead than the uk and are way better off but they still have quite a lot more death than sweden even if one looks at the excess deaths only and they are in lockdown.
Average age of stockholm is 38.5 and london is 40.5 so there is at least a little difference there.
Yes we are likely healthier but im not sure its that easy. I know nothing of Belgium really but arent they of quite good health to?