Let the sets are A = {1, 2, 3, 4} and B = {5, 6, 7, 8}
A – B = {1, 2, 3, 4} – {5, 6, 7, 8} = {, , , }
B – A = {5, 6, 7, 8} – {1, 2, 3, 4} = {, , , }
A ∩ B = {1, 2, 3, 4} ∩ {5, 6, 7, 8} = { } = ∅
∴ A – B, B – A and A ∩ B are sets.