The subdirectory check is used to monitor all the sub directories within a monitored directory. The user has the option to monitor all the sub directories or a particular sub directory [subdirectory name supports regular expressions] under the specified directory.

The file check is similar to the subdirectory check. The file check is applied to files instead of folders within a directory. Here too, the user has the option to watch for either all the files or a particular file [file name supports regular expressions] within the specified directory.

Know how file availability check works.

The two checks come under the Directory checks category. When the configured event occurs, an alert is raised.