Anno is more city builder. Definitely not Grand Strategy, arguably RTS.

I wouldn’t say they’re “incompatible” but they aren’t synonyms. I haven’t seen a grand strategy that is also an RTS, but I could see them co-existing potentially.

Grand Strategy is generally: you control a nation and operate on a map of the world (sometimes limited to a region). You’re continuously progressing your nation, constructing permanent buildings, unlocking permanent technologies, and improving your economy.

Examples: Europa Universalis, Crusader Kings, Total War.

RTS is: you control an army and win a battle on a relatively small map, where individual people are a relevant scale. You build units during the battle, but very few to no resources come into the battle from anything before, and very little to nothing changes after the battle.

Examples: Command and Conquer, Dune II, Starcraft.