From Bioinformatics.Org Wiki
People sometimes use "computational biology" when discussing that subset of bioinformatics (in the broadest sense) closest to the field of classical general biology.
Computational biologists interest themselves more with evolutionary, population and theoretical biology rather than cell and molecular biomedicine. It is inevitable that molecular biology is profoundly important in computational biology, but it is certainly not what computational biology is all about (see next paragraph). In these areas of computational biology it seems that computational biologists have tended to prefer statistical models for biological phenomena over physico-chemical ones. This is often wise.
One computational biologist (Paul J. Schulte) objects to the above and makes the entirely valid point that this definition derives from a popular use of the term, rather than a correct one. Paul works on water flow in plant cells. He points out that biological fluid dynamics is a field of computational biology in itself. He argues that this, and any application of computing to biology, can be described as "computational biology" (see also the "loose" definition of bioinformatics). Where he disagrees, perhaps, is in the conclusion he draws from this:
"Computational biology is not a "field", but an "approach" involving the use of computers to study biological processes and hence it is an area as diverse as biology itself."
"I do not think all biological computing is bioinformatics, e.g. mathematical modelling is not bioinformatics, even when connected with biology-related problems. In my opinion, bioinformatics has to do with management and the subsequent use of biological information, particular genetic information."