Amit Kumar Roy

Physics, Chemistry, and Biology are different aspects of science which are always correlated to one another and one will crumble down without the other and this section is way too small to differentiate one from the other. However, let's give it a try.

Physics as the name suggests deals with the physical aspect of science. Beginning with the fundamental properties, extended to the special theory of relativity and everything in between is physics. Matter and energy are rather quantitative to all branches of science and not just physics but it is worth noting that physics alone gives their qualitative definition and conservation principles. Based on what you're dealing with, you might want to classify physics under
Classical Physics - Newton's laws of motion, friction, electromagnetism, thermodynamics, optics, classical mechanics, fluid mechanics, wave theory are some points of interest
Quantum Physics - the atomic theory, quantum field theory, nuclear morphology, etc falls under quantum physics.
Relativity - all our favorite time travel concepts come under this category. Founded by none other than the pioneer of the field - Albert Einstein, it deals with the very fabric of space and time. The famous equation which relates matter to energy i.e.  comes from here.

Chemistry, well, is a study of what exactly will happen or is expected to happen if elements with different properties are brought in contact or made to react with each other under a given set of physical conditions e.g. temperature, pressure, humidity, etc. When you burn a candle, what you witness is the beauty of chemistry - the hydrocarbons reacting with the oxygen available in the atmosphere meanwhile emitting both light and heat, an exothermic reaction. Quantum physics is, more often than not, correlated to chemistry. Here, however, it deals with the different states of elements and their molecular orientation in space. Also, atomic theory and spatial orientation of atomic particles kick in every now and then. Chemistry in itself is classified under Physical, Inorganic and Organic Chemistry wherein it deals with different elements.

As for biology - it's everything you see around that can breathe, talk, walk, have emotions, or basically is living. Biology is a combination of physics with chemistry. You might not know but thousands of chemical reactions are taking place inside your body while you're reading this. Photosynthesis, the ground level production of food, is nothing but a chemical reaction. Locomotion at the same time is just one of the many implementations of physics in biology.

Though this is far from enough to differentiate these subjects from one another, I tried my best to brief the reader with the basics. Hope it helps.