Here's a breakdown of how we use the terms "fact" and "theory" in science:

* Fact: A fact is an observation or measurement that is considered to be true. For example, the fact that the Earth is round is supported by countless observations and measurements.

* Theory: A theory is a well-substantiated explanation of some aspect of the natural world, based on a body of facts that have been repeatedly confirmed through observation and experimentation. Theories are not guesses, but rather well-supported explanations that can be used to make predictions.

Evolution is a fact because we observe it happening in real time, both in the lab and in nature. We see species changing over time, and we can trace the lineage of these changes.

The Theory of Evolution is the explanation for how evolution occurs. This theory is based on a massive amount of evidence, including:

* Fossil record: We have a vast and detailed record of fossils showing changes in species over millions of years.

* DNA analysis: We can analyze DNA to see how closely related species are, and how their DNA has changed over time.

* Direct observation: We see evolution happening in real time in organisms with short generation times, such as bacteria and viruses.

It's important to understand that the Theory of Evolution is not just a hypothesis or an idea. It is a well-supported explanation for the diversity of life on Earth.