Synonyms disambiguation
Account id, account name, user id, username, user name, login, login id, and login name are often synonyms, referring to the concept of a unique identifier used by a subject to claim its identity.
With this meaning, the terms account name, username, user name, and login name are ambiguous because the term name implies that the unique identifier used by a subject to claim its identity is the common name of the subject (e.g., John Doe), which is wrong in many identity management systems (e.g., ad hoc naming conventions, email addresses, etc.). Thus, in this context, the term name should be discouraged.
With this meaning, the terms account id and account name are ambiguous because the term account, which is a synonym of identity, may lead to think that any identity identifier (e.g., identity system identifiers, identity profile display names, etc.) falls into this definition, and not only the unique identifier used by a subject to claim its identity. Thus, in this context, the term account should be discouraged.
With this meaning, the terms user id and user name are ambiguous because the term user, which is ambiguous by itself, may (or may not?) imply that the subject is a human being. In this context, the term user should be discouraged.
Finally, the term login id is more accurate than the above alternatives. It nicely embeds both the idea of an arbitrary symbol, the identifier, with the moment when that symbol is used to claim an identity, the login process.
But in practice, the above alternative forms are in widespread usage.