I recall when the DTC compounds first came out, the 70s and 60s were available at the same time...The 70 and 60 are both track pads but serve a slight different purpose. The 70 is designed for longer stints, like enduros so they have a higher heat capacity and they tend to last longer, plus they have higher brake torque but will eat the crap out of the rotors. DTC-60s are designed for shorter stints, like sprint races and DEs where sessions are about 20-25 minutes each.
Never tried the 70s on my car but the DTC-60s are by no means an "older" pad. They've only been out for 'bout 4-5 years. Equivalent to Cobalt XR-3 (XR-2 is like DTC-70) or PFC-01.