The shanty genre label itself is mostly retrospective.

The strongest correlation for work song method was in the size of the work party. A sailor could expect to perform in more than one mode, on any one given vessel/voyage, let alone an entire career.

The most rigid version says the largest crews worked in silence simply because they were large (eg: Royal Navy.) Not so.

The larger the work detail, the more likely a musician was hired. Fiddle, fife and drum, in that order. These “all-hands” anchor, capstan, windlass songs &c. were/are not shanties, nor were/are maritime musicians considered shantymen.

A typical six-eight man rowing crew (or brake windlass detail, as depicted in the Ytube videos) would be at the opposite end of that spectrum. Borderline to having a working crewman filling the role of song leader and saving the overhead of a dedicated middle manager altogether. A cohortive strokesman, as opposed to exhortive patroon. These were boat songs. Maybe “rowing” or “pulling” shanties in retrospect, maybe not. Depends mostly on who is doing the sorting. (eg: Edisto Island rowers.)

The bulk of the current, standard model, 'classic' shanty(man) genre lived somewhere in the middle. The exact boundaries… depends. And most of the time, folks will not have lyrics to sort by.