Domestication: When humans take an animal/plant species into captivity, and breed, modify, and adapt the species so every domesticated member of the species is a perfect candidate for food, materials, or service. For example, When wolves became a part of human's lives, the humans chose which wolves to breed, slowly creating what we now know as dogs.
Natural selection: The idea that whatever plant/animal is not adapted to suit its environment will wind up dead, leaving the well adapted survivors to produce more well adapted plants/animals. For example, If bird 1 is green, and bird 2 is brown, bird 1 is more likely to be spotted by predators and eaten; however bird 2 will be able to produce more brown birds.