conjunction & adverb
determiner & pronoun
In good English writing style, it is important that either and or are correctly placed so that the structures following each word balance and mirror each other. Thus, it is correct to say either I’ll accompany you, or I’ll wait here. The two expressed choices are parallel, as each includes the subject and its verb phrase: I’ll accompany you; I’ll wait here. It would be incorrect to say either I’ll accompany you or John because the first choice includes the subject and its verb phrase, but the second choice is just an object: I’ll accompany you; John. A corrected version could be I’ll accompany either you or John (now the choices are parallel, as each is just the object: you; John). See also neither (usage).