Yes, Linguist use Bergamot translator that is embedded in Firefox. But translation in Firefox in beta stage, it does not have a lot of features and does not support a lot of languages yet. Linguist is a full featured translator that support a lot of translation modules and even custom translators provided by users. So Firefox translation is just a subset of features from Linguist, like Firefox ads protection is just a small subset of features from uBlock Origin.
But Firefox translator are technological breakthrough anyway, so we appreciate it.
Thank you too 👍