Both push conditioned air into a room. Neither will do the other's job, and the reason is less about airflow than about what happens to them.
Side by side
| Floor register | Wall or ceiling vent | |
|---|---|---|
| Held in by | Its own weight | Screws, included |
| Walked on? | Yes, built for it | No |
| Damper | One opposed-blade on a lever | Three adjustable, smooth-glide |
| Finish | Powder-coated brown | Matte white powder-coat |
| Sizes | 2x10, 2x12, 2x14, 4x8, 4x10, 4x12 | 10x4, 10x6, 10x8, 12x4, 12x6 |
| Install time | Under a minute | Around fifteen minutes |
The real difference is load
A floor register gets stood on. Not occasionally, but every day, by everyone in the house, sometimes with furniture dragged across it. That is why it is stamped from heavier steel with an edge-folded faceplate, and why gauge is the thing worth paying for.
A wall vent never carries weight. What it has to do instead is stay flat against a surface people look at, and throw air out into the room instead of down the wall. So it gets more louvers, finer damper control, and screws to hold it true.
Why the sizes do not line up
This is the practical trap. Floor duct and wall duct are different shapes, so the size ranges barely overlap. There is no 4x10 wall vent and no 12x6 floor register.
Which means you cannot look at the register in your hallway, note the size, and order the same number for the wall. Go and measure the opening you are actually covering.
The colour thing
Our floor registers are brown. Everything else we make is white.
That is deliberate, not an oversight. Floor registers sit against wood, tile and carpet, where a warm matte brown disappears and bright white shouts. Wall vents sit against painted drywall, where white is usually what you want.
If you need a floor register in white, we do not make one, and it is better that we say so than sell you something you will end up repainting. Though if you do want to repaint, both finishes take paint well.
What about returns?
Different animal again. Both parts here are supply, which means air coming out. A return grille pulls air back to the furnace and has no damper at all. If you are not sure which you have, there is a ten second test.