There is no standards body that regulates the names of guitar sizes/styles. For electric guitars, people often use the names of Gibson and Fender shapes ("Strat", "Tele", "SG", "Les Paul") and for acoustics, people often use the names used by Martin ("0", "00", "000", "OM").
One manufacturer might happen to use the word "folk" for a guitar that's similar in size and shape to a Martin 000.
However, it would be unwise to rely on it. Find the actual measurements of the guitar.
Of course, what actually matters is how the guitar sounds and feels. Unless you're experienced and know the risks, never buy a guitar without having tried it out.