Ada and qada cannot be distinguished merely by the outward appearance of an act. The prescribed time and the nature of the obligation matter. Prayer within its assigned period is a straightforward illustration of performance; a relevant later performance belongs to the discussion of making up a missed duty.
Time may function as a container or, in certain duties, as a measure defining the obligation. Ask what the time limit is, which duty is involved, and whether a later act retains the same completeness. Such questions explain the book's finer categories of performance and make-up.