They are different. If you select "Cache type / size" it will use all your finds to fill the matrix but only show the selected type(s) as suggestions for filling in the remaining boxes. If you select "D/T type / size" it will only use that type(s) to fill your matrix (and also for suggestions).
Thus, if you want to complete your matrix with just one specific cache type, you need to use the "D/T type / size" filter.