These are changes in an organism's DNA that can lead to variation within a species. It’s like a coding error during a software update that results in new features.
This is the formation of new and distinct species through evolution. It’s like developing an entirely new version of your smartphone software based on user feedback.
As mentioned earlier, this is nature's way of choosing who gets to reproduce based on who is best adapted for survival. In our analogy, it would be like users deciding which software updates are most useful and keeping those while discarding others.