My understanding is, Esperanto has no definitive word order regarding subject, object, and verb.
And I also know one never uses -n for estas, example:
Urso estas besto. A bear is an animal.
However, there are larger categories, for example:
Besto estas organismo. An animal is an organism.
Without the word order like in English, it seems we would have a problem of ambiguity: One could say "A estas B" or "B estas A" to mean the same thing, while they don't.
Is this true? If it is, how to reduce ambiguity in such situations where a something could be an animal, and an animal could be another thing? If not, how do we know?