I’ve noticed that some websites feel very similar even though they use different names. Is there a simple way to understand whether they are connected?

Yes, that is where checking a sistersite can be useful. It can help show whether different websites are part of the same wider group or share parts of the same underlying structure. I usually look at things like ownership information, support details, account setup, and general terms rather than relying only on the design. That makes it easier to understand whether two sites are genuinely separate or simply presented differently.