Third person and Third party

Third person noun - Pronouns and verbs that are used to refer to something other than the speaker or addressee of the language in which they occur.

Third party and third person are semantically related. In some cases you can use "Third party" instead a noun phrase "Third person".

Third party noun - Someone other than the principals who are involved in a transaction.

Third person and third party are semantically related. You can use "Third person" instead a noun phrase "Third party".