Organic chemistry, also known as “carbon chemistry”, is chemistry involving organic — or “carbon-based” — molecules. All life on Earth can be considered an expression of complex carbon chemistry. However, since lots of non-living things are carbon-based as well, organic chemistry isn't merely limited to biochemistry. Organic chemistry also deals with polymers, petroleum products, and much more.
Constitutional Isomers — have the same chemical formula (i.e., the same number of every kind of atom) but are put together in entirely different ways.
For more information, please see stereoisomer.
Conformational Stereoisomers —