This article entitled Software Engineering, Not Computer Science (PDF), is probably the clearest definition of the difference between the two fields that I have seen to date. It also provides very interesting food for thought because many yearn to do computer science, yet most of us are employed doing software engineering.
In a way, it is a pity that there are not more computer science jobs available. I have encountered a few really smart people who love the discipline and would no doubt advance the field of computer science if they were given the chance. They just made absolutely horrible software engineers as they were not really interested in producing products. They were only interested in creating new things, no matter how unrelated or inapplicable to their task at hand.