What is actually in here
Vanity cabinets without tops lead the range, then hutches, drawer units, base cabinets, storage cabinets and linen cabinets.
Those are six different jobs. A hutch sits on top of a vanity and takes the wall above it. A linen cabinet is a tall unit standing on the floor. A drawer unit fits between two vanities in a double arrangement. They are not variations on each other. Bathroom vanities is the basin unit itself.
The widths are narrow
The sizes run 12, 15, 20, 24, 25, 39.5, 48 and 60 inches, and the small end of that list is the useful part.
A 12 or 15 inch cabinet exists because bathrooms have leftover wall: the strip beside a vanity, the space between a vanity and a lavatory, the run under a window. Those are the gaps a bathroom actually has, and a cabinet that fits one of them is worth more than a wider piece that does not fit anywhere.
Solid wood, mostly
Poplar leads the materials, with yellow poplar, ash, parawood and a general wood group behind it.
Solid wood in a bathroom moves with humidity and can be refinished when it does. It also means these pieces are joinery rather than board products, which shows at an edge and at a corner and is part of what separates a bathroom cabinet from a flat-pack one.
The finishes match the vanities
Glossy white leads, then mid-century acacia, walnut whisper, bright white, honey oak, black onyx, pecan and a smokey celadon.
Those are the same finish names the vanity range carries, which is the point of buying storage from the same source. A cabinet beside a vanity in a nearly matching white is worse than one in a deliberately different color, because a bathroom is small enough that the two are always seen together.
A hutch is a wall decision
A hutch sits on the counter and occupies the wall behind it, which is the wall a mirror would otherwise have.
That is the trade nobody mentions: a hutch gives storage at eye level and takes the mirror position with it. In a bathroom with one basin and one wall, choosing between them is the actual decision rather than choosing which hutch.
A cabinet without a top
The largest group here is vanity cabinets supplied without a top, which is a different purchase from a vanity.
It exists for two situations: a bathroom where the counter runs across several units as one piece, and a replacement where the existing top is staying. In both the cabinet is joinery being bought on its own, and the width has to match what is above it rather than what is beside it.
Where these go
Beside a vanity, above one, between two of them in a double bathroom, along an empty wall or in the gap under a window.
The one place they do not go is where a basin is wanted, which is the distinction the whole collection rests on. Single vanities and double vanities carry the basin units, and bathroom mirrors the wall a hutch would otherwise take.