What is the difference between clean and delete?

After I saw this image, I wonder what is the difference between clean and delete?
http://www.majorgeeks.com/screenshots/n/nod32.jpg

 

some malware, like macros, can be cleaned from teh file leaving the that file useable.

delete well, deletes the file.

 

so the Clean is like removing the "poison" but the malware still exist/usable?

 

Clean removes the malware but leaves the file. the file usually being a document.

 

Viruses (file infectors) can be cleaned from infected files. Other malware (trojans, backdoors) can only be deleted.
It seems that in your case this virus hasn´t infected clean files, so deleting it would be fairly safe. Before any action, make a copy of it into the quarantime.