DSL is a generic term we use to encompass both ADSL (Asymmetrical Digital Subscriber Line) and VDSL (Very-High-Bit-Rate Digital Subscriber Line). ADSL uses mostly copper cabling and older technology while VDSL encompassed fibre components and newer exchanges for higher throughput.
ADSL is capable of maximum 20Mbps (in terms of Telkom's infrastrcuture, the technology itself can handle higher speeds) and VDSL is capable of speeds up to 40Mbps (also limited by Telkom's infrastructure).
Both ADSL and VDSL use existing copper cabling to your home. This does not include newer products like Fibre to the Home.