For questions related to a method of study that increases interval of time between reviews of older, more experienced terms.
Questions about spaced repetition software (SRS) programs, the digital equivalent of paper-based flashcards.
To be pedantic, the latter talks about computer programs, whereas the former doesn't - it can encompass dead tree methodologies such as the Leitner system. But I don't really see the point of having both tags.
There ain't enough space in this Stack Exchange for the two of them.