The difference between the two can arise from architecture and run-time dependent factors, e.g. programmed delays or waiting for system resources to become available.
This means that while the program was active for six minutes and one second, during that time the computer's processor spent only 4/100 of a second performing calculations for the program.
Since in concurrent computing the definition of elapsed time is non-trivial, the conceptualization of the elapsed time as measured on a separate, independent wall clock is convenient.
[1] The term wall-clock time has also found widespread adoption in computer simulation, to distinguish between (1) the (often compressed or expanded) simulation time, and (2) the time as it passes for the user of the simulation tool.
You can help Wikipedia by expanding it.This time-related article is a stub.