If Bina goes to the party, then both Inga and Mary will; but if Bina doesn't go then neither will Mary or Inga.

Bina will both go and not go to the party, and so will Inga and Mary.

If Bina goes to the party, Ingal and Mary will both go; but if Bina doesn't go only one of them will.

Either Bina will go to the party, or Mary and Inga will not go to the party.