The DSL family has around a dozen variants, though some are now obsolete or unused in Australia. The most important are:

ADSL (Asymmetric DSL) for consumers and small business – which has more capacity from the network “down” to the user then capacity “up” to the user.
SDSL (Symmetric DSL) for business – which has the same capacity “up” and “down”.
SHDSL (Symmetric High bit rate DSL) for business – which provides symmetric services at higher speeds (eg. 2Mbps) than SDSL.
When discussing DSL generically, the expression “xDSL” is often used.