Scientific laws differ from theories in that they tend to describe a narrower set of conditions. A scientific law might explain the relationship between two specific forces or between two changing substances in a chemical reaction. Theories are typically more expansive, and they focus on the how and why of natural phenomena.
Both scientific laws and theories are considered scientific fact. However, theories and laws can be disproven when new evidence emerges. Certain accepted truths of Newtonian physics were partially disproven by Albert Einstein's theory of relativity. The work of Louis Pasteur disproved prior theories of disease in animals. If thorough scientific research upends a previously held belief, scientists must find new hypotheses that better describe how nature works.
