stream_get_contents是否比file_get_contents更低级别且更快?

From a comment to this answer I read that "stream_get_contents is low-level" comparing to file_get_contents. However according to Manual, stream_get_contents is

Identical to file_get_contents(), except that stream_get_contents() operates on an already open stream resource and returns the remaining contents in a string, up to maxlength bytes and starting at the specified offset.

Which statement is correct? Is stream_get_contents really lower level and faster?

Specifically I am interested in reading local files from HD.