Positive duty puts an obligation to do an act, on the part of the person on whom it is imposed. A negative duty implies for bearence /refrain on the part of person on whom it is imposed.

If A bought a car from B, then B is under obligation to hand over the car to A. Here B is subject to a positive duty.

If A possess a house then other are under legal duty to not to interfere in the legal enjoyment of the house. Here others are subject to negative duty.