@trinsec Oh! I do woodworking regularly, I can chime in here for definition clarity:
Staining works by applying a dye to the inner fibers of the wood; it leaves the grain of the wood visible (and often accents it), and penetrates ~1-2mm into the wood itself (depending on grain porosity).
Paint is almost always applied after a primer coat (to prevent the wood from absorbing it and causing some areas to look less painted than others), and contains pigments, rather than dyes, and sits on top of the primer layer.
Both stains and paints require a sealant on top of them (or built into the product itself) that is typically a polymer such as poly-urethane, an epoxy resin, or some sort of "hardening" (read: polymerizing) oil such as tung oil, or urushiol lacquer (super high-end Japanese woodworking finish). Multiple finish coats are usually required, and sanding between coats (unless you're using a self-wetting lacquer) is almost always the best policy to prevent the coats from building up unevenly.
The final coat is what provides the desired amount of sheen to the surface, along with the finish-coat composition, and method of application. For example, shellac can achieve a very high gloss with fairly little effort via the "french-polish" technique, whereas an epoxy finish is much harder and will require a floor buffing pad and a series of polishing compounds to achieve the same gloss.
Also, in your particular case, the (at least American English) term would likely be staining, even if it's a commercial, 2-in-1 product that contains both a dye/stain and a finish compound for protection. Another good way to tell the difference is paint is almost always opaque in the can, whereas stain is translucent or looks kinda like a decarbonated soda.
@johnabs Mmm, when we bought this pot of stain in the store we had a lot of choice in colors. It could be transparent, it could be semi-transparent, or it could even be opaque. They're all stains.
I went for a strong green that's a bit transparent so that you can still see some wood lines beneath.
We only have to apply it once and it's good, the store clerk said. So it's probably one of those all in ones. Screw sanding and buffing. ;) We already cleaned those old planks with high water pressure, that's good enough.