What is the difference between iCloud Drive and iCloud, you might ask? I, too, had this question, and this article helped me understand both much better. If you decide to read this, the first article covers iCloud Drive, and if you keep scrolling the second article covers iCloud.
One nice feature is you can access both from any device. Presently I'm on my computer running a Linux OS but I just logged into my iCloud account from the browser and in iCloud there appears an iCloud Drive icon. After clicking the icon it opens and shows me what's stored in my iDrive.
Here is yet another article discussing the difference between the two functions that you may also find helpful.