Intraspecific Competition: This is competition between members of the same species - like guests at the party all wanting the last slice of pizza.
Interspecific Competition: This is competition between different species - imagine if you had dogs and cats at your party both wanting to eat the same bowl of pet food.
Predator-Prey Dynamics: This refers to interactions between two species where one species (the predator) feeds on another (the prey) - kind of like if some uninvited 'party crashers' showed up and started eating all the food meant for your invited guests.