Gharīb as an isnād classification: a report involving an individual narrator's uniqueness at a relevant point in its transmission. The inquiry concerns chains and transmitters.
Gharīb as vocabulary: an uncommon word or expression in a hadith text. The inquiry concerns language, sense, and context.
A well-attested hadith can still contain a rare word. Conversely, a hadith transmitted through a single distinctive route may use entirely common vocabulary. One kind of “strangeness” therefore cannot prove the other.
Research rule: Consult isnād comparisons for uniqueness in transmission and linguistic works on gharīb al-ḥadīth for the meaning of unfamiliar wording.