A linguist is a person who has studied or is interested in the science of language. A polyglot is a person who can speak, read or write in several languages. Modern dictionaries often describe linguist as someone who can speak many languages, but for people in the field of linguistics there is a distinct difference.
Knowledge of Rules and Syntax
The very words were very cleverly twisted but their verity maintained.
A linguist will be able to tell you that the first very is an adjective, the second very an adverb, and that verity has nothing to do with very. He will also be able to tell you why twisted is in participle form, that –ed is a time-bound morpheme.
A polyglot, on the other hand will know this sentence to be correct, can independently make this sentence up, but may not necessarily be able to explain the logic behind each word.
Application of Multiple Languages
A linguist could have studied more than one language structurally, yet may not speak more than one language. He will be able to tell you that English has Germanic roots, Hindi is Indo-European. He will probably tell you that the root “qtl” signifies any kind of killing in Arabic / Urdu (Just like the suffix “-cide” – suicide, insecticide, matricide, homicide – in English), and may know many other prefix combinations with their meanings. But he need not necessarily speak Arabic – or for that matter anything other than his native language – to have studied that.
A polyglot, while he may not be able to explain rules and syntax of a language, can communicate very fluently in his languages and is able to use the most complex of structures or expressions with remarkable ease. Fluency in language is most often instinctive.
Are linguists and polyglots mutually exclusive?
Not necessarily. Because of their interest in languages, many linguists happen to be polyglots too. But all linguists are not necessarily polyglots; many are monolingual.
Polyglots may be multilingual either because they were raised in a multilingual or multicultural environment, or because of a conscious decision to learn more languages. But all polyglots are not necessarily linguists. Many people from Europe, Africa and the Indian subcontinent are polyglots, given their diverse culture and history of colonization.