If I have an account on Mastodon.Social, and another account on PieFed.Social are they technically on the same instance, since they're both on .Social?
If I have a house in Orange County, California, and another house in Orange County, Florida, do I technically only have one house since they're both in Orange County?
No. I see you making fun of someone for asking a question. They are trying to apply some of their knowledge to something new. What they have learned from some other good answers is useful going forward.
Sadly, it seems you need to learn more to be able to understand where this person is coming from.
I mean, it communicates the same point. The two are unrelated even though they have the same county name, just like websites share the same TLD and are completely unrelated to each other.