How can the processes of parasitism and predation be different if they both harm organsims?

The similarity between predators and parasites is that both acquire energy by taking that energy from other organisms. It positively affects one organism (the predator or parasite) while negatively affects the other organism (the prey or host organism). But, the main difference is that predators tend to kill their prey while parasites don’t. Parasites only take resources from their host.

This is giving me a headache i have asked others and they don’t know it either