One organism benefits while the other is killed.

This is called Parasitism.

One organism benefits while the other is killed, this relationship is called parasitism.

Explanation:

Parasitism is symbiotic relationship between two organisms in which one gets benefit and the other get harm. Those organisms which feed on other organisms and causes damage to them is known as parasites. There are two types of parasites. Those parasites which lives inside the host body is called endoparasite while those parasites which lives outside the body of host is known as exoparasite.