File Open and File Execution Setting differences?

What are the differences between those two? Ty

 

"Scan on Open" specifies that files are scanned when they are opened for any reason. This setting catches malicious non-executable content, such as PHP shell scripts, trojaned PDF files, and javascript iframe injections.

"Scan on Execution" specifies that files are scanned when they are opened for the purposes of executing machine code, such as malicious EXEs and DLLs, before they are loaded into memory.

Someone else may have further clarification on these settings, but as far as I've been able to observe in filemon and procmon, that's pretty much how they work.