@357433936 said:
The difference between api key and api key (v3auth)
I only have API KEY，I want to know the difference between api key and api key(v3 auth).

There are not two API Keys.
There is the API Key and the Bearer Token.
See here: https://developer.themoviedb.org/docs/authentication-application

When you have an API Key, used in v3, you automatically also have a Bearer Token, used in v4 and v3.
See here: https://developer.themoviedb.org/reference/intro/authentication
I suggest spending some time reading the instructions.
I personally don't use Token, so I can help you.