Simple Security Clarification

In another thread [How do you protect individual files], Justin French stated: "In real short, you want to store the files outside your htdocs root (so they can't be served by http) . . ." My PHP setup serves files from DOCUMENT_ROOT=/var/www/html. If I place files in '/var/www/html/secure' would this provide any isolation for file access? Am I correct in thinking that 'below' is not the same as 'outside' doc_root, and that i this case, no protection would be afforded? Tia, Andre