Natural selection and genetic drift are important parts of how species change over time. They work in different ways.

Natural Selection:

• This happens when some individuals have traits that help them survive better than others.
• For example, if you have a group of beetles, and green ones are easier for predators to see than brown ones, the brown beetles will likely survive longer and have more babies.
• As time goes on, more beetles will be brown because of this survival advantage.

Genetic Drift:

• This is about random changes in the traits of a group. It often has a bigger impact on smaller groups.
• For example, if a flood destroys many flowers in a small area, the flowers that survive may not represent all the different traits that were originally there.
• One famous example is the “Bottleneck Effect.” This happens when a big group suddenly becomes very small, like after a natural disaster, which reduces the variety of traits in the group.

In short, natural selection is a way that helps some traits become more common based on their benefits, while genetic drift is random and can change traits in a group without caring if they're helpful or not.