The way I've always looked at it is that #include <filename> is to bring in "standard" header files such as those under /usr/include, whereas #in

The way I've always looked at it is that #include <filename> is to bring in "standard" header files such as those under /usr/include, whereas #include "filename" can bring in any file at all, and located anywhere at all, that could be useful, be that a normal header file; or a C-code file with functions, etc; or even a binary blob. (Though I usually convert binary blobs to ASCII C-style data headers in my own program coding.)