Posted: Sat Mar 27, 2021 9:29am
I can’t comment on the other countries - I really don’t know; but differences between Residency and Citizenship - Permanent Residency grants you the right to reside and work in Spain, and vote in local municipal elections. You are still restricted to the 90 days in 180 in other Schengen countries though; your residency is theoretically all you need to carry in other countries, but your UK passport will restrict your movement. (I specify permanent residency, because for those now settling in Spain on an NLV, remunerated employment is forbidden until permanent residency attained - 5 years)
As a Spanish Citizen, you are obliged to renounce your British Passport ... but that is never checked up on. A citizen has all the rights - and obligations - of a natural born Spaniard; i.e. can move freely throughout EU, live, work, settle in any EU country etc etc and can vote in local, national and EU elections. If you are of age it also renders you liable for military service should the country deem it necessary in time of crisis. There is no conscription here, but it’s pretty much the same as any country where you are citizen as opposed to resident, you have obligations as well as rights.
As a permanent resident, you can be out of Spain for up to 5 years without losing residency, but there is that time limit. A citizen will of course have no limits placed on how long they can be out of the country, save those placed upon them by whichever other country they visit. If that’s another Schengen country, then in reality a citizen can spend 20 years away from Spain and still return. A resident can manage 5, and that’s with the associated issues of being a TCN now having to apply for residency in another country - I don’t know if that would invalidate Spanish residency or not - I suspect it would, because of the aforementioned 5 year rule - you’d have to be resident in the other country for 5 years to become a permanent resident, at which point Spanish residency lapses.
It’s quite possible the route to citizenship is easier in other countries and can indeed depend on how much money you are able to “invest in your future”, but I really don’t know - although I can say that Portugal has a lower income threshold for residency than does Spain