It is common to confuse the terminolgy when discussing coin acceptor products, here we discuss to clear the confusion by explaining some of the common terminology in detail.
Coin Acceptor, Coin Selector, Coin Validator: These are all common terms to describe a device that reads and validates a coin (or token) and reports it's 'finding' via an interface (pulse/parallel, USB, MDB, etc) to a controller. The more simple of these devices will only validate 1 specific coin or token. Multicoin devices can read multiple coins and generally can come pre programmed or have some field programibility.
Coin Changer: This term is commonly used for a device used in some sort of vending machine (soda, snack, etc.). The device generally comes with a coin validator and has between 3-6 tubes that recycle the coins used as change in the machine. Some coins replentish these change tubes and some may pass straight through to the 'drop'.
Bill to Coin, Coin to Coin Changer: This device should not be confused with the above device. A bill to coin changer is a device that would include a bill validator and coin hoppers internal to some form of enclosure. Typically used for 'breaking' a bill (paper money) into coins or tokens. In countries with higher value coins, this device may also have a coin acceptor to drop through a high value coin for coins of lesser value.
There are also specialty forms of coin 'validators' such as a 'Bulk Coin Acceptor' that would take a large amount of coins, droped into a 'bowl' that would then circulate the coins through the coin acceptor.