Physics and chemistry are two fields of science that study matter. While the subjects studied are similar and may even overlap, the approach each field takes is the main difference between the two. Chemists study matter at a molecular level, while physicists study the mechanics of why matter reacts in a particular way.
Chemistry studies the activities and properties of all inorganic and organic matter. A scientist may choose to focus his work in general chemistry or specialize in either inorganic or organic chemistry. Chemistry procedures are reproducible, and all theories or hypotheses are tested in order to verify reliability of the hypotheses. Chemistry deals with the chemical composition and reaction of matter.
The science of physics also involves the study of matter and energy and how they interact with each other, but physicists are generally looking for the base answer as to why or how matter reacts the way it does.
Physicists study the entire universe as well as small-scale matter such as subatomic particles, but the basic principles revolve around the forces of nature taking place and how they work. Chemists may also study matter on a large scale, but the basic principles of chemistry ultimately focus on how matter reacts at an atomic or molecular level.