In Real-time qPCR, we run the reaction for 50 cycles and monitor its progress during each cycle to examine the efficiency of our assays. Because we can monitor the progress during each cycle, we can make an estimation the number of copies in the original sample.

In end-point PCR, the reaction is run for as many cycles as possible and then checked at the very end for amplifications. End-point PCR allows you to see positives, but we do not get the concentration of DNA.