Predation
Predation is the interaction between two organisms when one (the predator) feeds on another organism (the prey). Moreover, the predator benefits from predation by consuming the prey's energy.
If the predators above were to be extinct, then the population of their preys will rise and essentially interrupt the food chain. Therefore, predation is an important short term relationship between two species in order to keep the mother nature in balance.
Competition
Competition is an interaction between two or more organisms that occurs when they compete for the same resource. Indeed, an organism's ability to reproduce and develop reduces as competitions occur.