Domains have restrictions based on the rules of their registrar, that may be mandated by the government of the associated country.

Some old examples are .gov, .mil, .edu. - I believe that only US Government entities can register with .gov - Not just federal entities but also state and local entities. For example. https://www.sf.gov/ is the San Franscisco City Government site. I’ve also seen things like https://abcab.ca.gov/ that actually use the hierarchy that was originally intended to exist in domain names. Similarly, .mil is for US military organizations.

.edu must be an accredited institution located in the United States, for example https://harvard.edu/.

If you’re in the United Kingdom, you can get a .uk domain, and there appear to be special subdomains with specific use, for example, colleges and universities are .ac.uk, although I don’t know the specific details

.com, .net, .org, .info, .biz are all free-for-alls and no one cares if a commercial entity registers a .org or vice-versa.

Trust any information you find on the internet as much as you trust the author. If you don’t know personally know the author, well, then, how much do you trust random strangers on the street handing you fliers?

You can read more history on gTLDs at the Wikipedia page https://en.wikipedia.org/wiki/Generic_top-level_domain