How do evolution and natural selection differ?

Population variation in traits that bring about differences in fitness (defined as an organism's capacity to survive, reproduce, and produce viable offspring) and that these variations will be passed on to the trait bearer's progeny are necessary for evolution to occur in a population.

The mechanism that will choose the people who are more fit is called natural selection (since their offspring will form the next generation).

Natural selection is one of the mechanisms of evolution (the others are genetic drift, mutation, and migration). Evolution in general refers to descent over time with modification. Evolution generally happens over long period of time.

Natural selection is what most people think of when they think of evolution. Within a population of breeding individuals, you have variation in their genetic traits. Those traits are passed down from parent to offspring and those traits that help individuals survive are more likely to be passed on.

Since different populations of the same species are not confronted to the same selective pressure, different genes will be selected for in different populations. After a certain period of time (usually a very long time), those populations move towards different species.

As change is by definition, evolution is commonly used to refer to Darwinian evolution, or descent with modification, which is the theory that all life began as a simple cell and "evolved" or changed into all the complex forms of life that have been observed in the world.

Darwin incorrectly believed that there was infinite potential variation in all living things. Gregor Mendel demonstrated that normal sexual reproduction was wholly conservative and that no new information is created in sexual reproduction. Darwin proposed that natural selection was the process by which organic evolution occurred.

Darwin postulated that natural selection would choose the best-adapted variations and lead to the extinction of less well-adapted ones, creating a natural progression from the simple to the complex. Darwin believed that there could be an infinite number of variations.

Neo Darwinian evolution suggests that new forms are created by random accidental mutations in the DNA, and that natural selection selects the favorable mutations to preserve and the extinction of less favorable mutations. Natural selection can only cause the extinction of less well adapted forms.

Natural selection is proposed as the mechanism by which Descent with modification occurs. Evolution is change; Darwinian evolution suggests that the change goes from the simple to the complex despite the empirical evidence that change always goes from complex to simple.

Evolution refers to the gradual change in species over time, while natural selection is one mechanism driving evolution, where individuals with advantageous traits are more likely to survive and reproduce, passing on those traits to future generations.