Robin Hanson cites Eric Drexler’s new book on science versus engineering:
Scientists seek unique, correct theories, and if several theories seem plausible, all but one must be wrong, while engineers seek options for working designs, and if several options will work, success is assured.
Scientists seek theories that apply across the widest possible range (the Standard Model applies to everything), while engineers seek concepts well-suited to particular domains (liquid-cooled nozzles for engines in liquid-fueled rockets).
Scientists seek theories that make precise, hence brittle predictions (like Newton’s), while engineers seek designs that provide a robust margin of safety.
In science a single failed prediction can disprove a theory, no matter how many previous tests it has passed, while in engineering one successful design can validate a concept, no matter how many previous versions have failed.
I taught engineering for 37 years at colleges and universities and worked with scientists and other engineers on various research projects.
I think there are two major differences. First, any engineering project needs closure. At some point during the design/analysis you have to say, OK let’s do this. At that point alternatives are discarded, and the work proceeds. Scientists neither require nor even want closure. One physicist told me a few years ago that he hoped that the LHC did not find any of the five Higgs particles because the discovery would close off all sorts of research avenues. The Theory of Everything would essentially shut down much of physics research.
Second, engineers are held professionally, civilly and criminally libel for their actions and words. No scientist is ever held responsible for anything they say or do regarding science. That is why the indictment of the Italian seismologists a couple of years ago raised such ire among scientists.
It is also important to recognize that individuals sometimes act as engineers and other times as scientists. Quite a bit of basic research comes out of engineering departments, and Oppenheimer and his colleagues on the Manhattan Project were classical engineers.