mmm, I think I'm getting it.

The private key has a public key, which in my case looks like npub1qqqqqqqqqqqqqqqqqq9t....., that key is derived from my private key and is unique.

My handle: @Decentralized, can be changed to @Johndoe if I want, but what I can't change is the public key using the same private key, they are a unique pair.