What's the point of having different Build Configurations for Debug and Release?

What's the point of having different Build Configura开发者_开发问答tions for Debug and Release? Must we do anything different in the Release Configuration before building the app for distribution over the App Store?

I don't know about the iPhone specifically, but often (i.e. on other platforms like Windows and Linux) the so-called "debug build" includes debug symbols and disables compiler optimizations (to make debugging easier), whereas the release build doesn't (which makes it harder to debug, but faster and smaller and less easy to reverse-engineer).

See also Separate ‘debug’ and ‘release’ builds?