Is this physical levels (such as of a building) or figurative ones (such as of a skill) or both?
Typically the latter, although I guess you could use it for height level. It would be an unusual exception for sure.
I apparently missed this question two years ago. You probably know by now, but for the benefit of other learners: samma never takes the definite, and there's no real reason for it other than "that's just how it is".
What about nivån? Although I expect it's also "the way it is", there are so many cases where English and Swedish differ over definite/indefiniteness.
Oh I remember learning that now :) There are a few other adjectives like it.
Let me pick your brain once more. What if the noun is an ett-word, how do we know if it's plural or singular in these cases?
e.g. "Vi har samma jobb."
Do you simply avoid an ambiguity like that or do you clarify it somehow? (maybe by including an article after all, or something)
You're right - there's no way to derive the number grammatically. One can rewrite, clarify, or make it clear through context. I wouldn't say there's a single clearly superior option, so you're free to choose whichever suits you the best. :)
I love the French influence on Swedish... nivå = niveau. Very easy to remember
That would be på samma våglängd in Swedish. På samma nivå in this sentence could refer to a computer game or some kind of skill. Or maybe your Duo level :)