startup vs. boot features

[Ryan Moquin]

I was wondering what the difference is between startup and boot features.
 I was experimenting with starting up some of my features in a custom
distribution as a startup feature, but I received a lot of dependency
missing issues, it seemed like startup features were starting before the
boot features?  Is that correct behavior?  Or could this be the result of
mistake I'm making elsewhere?  Want to make sure that I'm interpreting what
startup features are properly.