Usually when folks ask for stain, and it happens a lot, they don't mean stain at all. They want it to be sealed, be finished with polish, or just assume that stain is used on everything wooden. And I get that- I used to think the same thing before I got into woodwork. Of course I will always recommend and do the best treatment on your custom build from my woodshop.
But if you want to be better equipped with wood finish knowledge, I made you a list:
Stain = changes color. Literally stains. No, I won't do this to the reclaimed wood I harvested, dried for two years, cut in ways that made the grain pop, and placed in the build to show character. And you don't want me to, either :)
Oil = Brings out natural color. Seals. It's great. My favorites are Tung Oil, Boiled Linseed Oil, or Orange Oil.
Shellac = A natural finish made from secretions of the female lac bug. I don't really use this on tables because it can be affected by heat.
Lacquer = A spray-on high gloss finish made of shellac and alcohol. Because of how involved this process is, it is the most expensive.
Polyurethane = Plastic coating. Brings out natural colors, though not as much as oil does.
Oil & beeswax = Same as oil, make it feel smoother to the touch. Makes it repel more water.
Varnish = Resin dissolved in a liquid. Spar Varnish is what we'll use for outdoor furniture. It has more solids in it and protects better from UV rays and weather.
"Sealer" = interchangeable term with all the above *except stain*. All seal to varying degrees.
Just beeswax = It's been requested. But it doesn't exist as a finish. Go ahead and try evenly spreading a candle all over your table!
Whitewash = Two definitions. 1) white paint, perfectly covered. It's white now. 2) white paint thinned out a lot, put on with just one pass and thinly. Makes it look a bit aged/faded.
Oxidized = A formula is used to rust the wood, making it look like it was exposed to the elements for years and years.
Shou Sugi Ban = Blasting the visible elements of the wood with fire, charring it. Lightly sand the char, raises the grain, color, and shine. Needs finishing after still.