Best comparison (car/machine manufacturing vs software development) I've ever heard on this topic is as following; While producing a machine, there are two ste

Best comparison (car/machine manufacturing vs software development) I've ever heard on this topic is as following; While producing a machine, there are two steps; 1) designing the blueprint (takes a lot of time, unpredictable) 2) mass production (takes a lot of time, predictable) Those steps in software development; 1) building the software (takes a lot of time, unpredictable) 2) deploying the code (takes virtually no time, predictable) So the real difference is this: software is almost all about doing something new, each and every time. It's all flesh and has no bone: e.g. devoid of a long, very stable and predictable mass production stage. It's almost all about R&D, all of it's length. Hence 98% of the process is novel work therefore takes time and hard to predict.