цитирую:
require() and include() are identical in every way except how they handle failure. include() produces a Warning while require() results in a Fatal Error. In other words, don't hesitate to use require() if you want a missing file to halt processing of the page. include() does not behave this way, the script will continue regardless.
для инглиш-инкомпатибл товарищей объясняю, require при отсутствии подключаемого файла вызовет fatal error а include лишь warning. фирштейн?