Tru-oil is a Birchwood Casey brand name. It's a blend of linseed and other natural oils with dryers and hardeners in it.
Tung oil comes from the dried and pressed fruit of the tung tree. It was originally used to waterproof the masts of Chinese boats. It penetrates wood to about 1/4" and gives a nice satin sheen when rubbed in. More rubbing and it'll shine more. It waterproofs the wood, brings out the grain and darkens the wood slightly. Once it's on, there's no going back though. Stain can be sanded off, but the oil stays put and you cannot re-stain.
There are also Tung Oil Finishes(Minwax makes one) made that are not pure tung oil. They have the hardeners etc in them to speed drying. They're not the same as pure tung oil. They work just as well, but it's not the same.
Both can be found in the paint section of any hardware store. Just be sure of which one you want. Not cheap either. About $15 a litre last time I bought some. A little goes a long way though.
None of those gaudy stocks have oil finishes. Looks like polyurethane(also found in the paint section) on paint to me. (That first one is a nice piece of wood and should have a hand rubbed oil finish, not plastic, if you ask me.) Scratch one and you'll have to refinish the whole thing. Scratch an oil finish and you just rub in more oil.