Lifecycles are either sequential or iterative. But there's a lot of differences in the lifecycles, and many more models than usually assumed. For example spiral development, throwaway prototyping, evolutionary prototyping, staged delivery, design-to-tools, design-to-schedule, modified waterfall (a sequential, iterative process) and more.

Read McConnell's 'Rapid development' for a walkthrough of the ones above and then some.