Create a set DifferenceΒΆ

S4 = S1 - S3

Create a Set Difference.
S1 = set(["apple", "mango"])
S2 = set(["mango", "orange"])
S3 = S1 & S2
print(S3)                                      # {'mango'}

#Set difference
S4 = S1 - S3
print(S4)                                      # {'apple'}