hmmmm.. The public_html folder is typically the actual physical folder and the www is just an alias for that folder. technically, public_html dir is where your site should be uploaded and if you delete your public_html dir then you deleted your website.
They are exactly the same, in fact, WWW isn't even a folder, it is just a shortcut to public_html. If you change something in either folder, the change will be reflected in the other. In short, it matters not which folder you use.
that might be a confusion.. depends.. some web softwares requires www dir..
public_html is the actual folder..
when you upload your site in www dir, your site is blank..
even when you delete the www dir it doesnt matter,
however it is not a good idea to delete default directories in your file managers...