Some Buddhist rock-cut caves are called Chaityas, while the others are called Viharas. What is the difference between the two?

Some Buddhist rock-cut caves are called Chaityas, while the others are…

Vihara is a place of worship, while Chaitya is the dwelling place of the monks
Chaitya is a place of worship, while Vihara is the dwelling place of the monks
Chaitya is the stupa at the far end of the cave, while Vihara is the hall axial to it
There is no material difference between the two

Answer

(a) Incorrect. A Vihara was primarily the residential monastery/dwelling place of monks, not the worship hall.
(b) Correct. A Chaitya was the prayer/worship hall, usually containing a stupa at the apsidal end, while a Vihara was the monastic residence.
(c) Incorrect. The Chaitya is the entire worship hall, not just the stupa; and the Vihara is a separate residential structure, not the axial hall of the chaitya.
(d) Incorrect. There is a clear functional difference: Chaitya = worship, Vihara = residence.