include_once vs require_once

hey folks, i'm wondering about the difference between include_once and require_once. the manual says The require_once() statement replaces itself with the specified file The include_once() statement includes and evaluates the specified file so, what is the difference? it's almost like one is a copy/paste and the other is some kind of read. is there any different behavior we should expect in scripts using one method vs another. my first guess was that require_once wouldn't evaluate the file, but i can execute code from within a file using either method. thanks, mike -- mike cullerton