There are more carbon compounds than there are compounds of all other elements combined. The study of carbon compounds, both natural and synthetic, is called organic chemistry. Plastics, foods, textiles, and many other common substances contain carbon.
In a nutshell, Google Backup and Sync is a combination of Google Drive and Google Photos. There is no need to use two separate apps, as you can do it all with a single tool. Though, it is missing an easy way to restore the backup.
Dropbox and Google Drive are file storage services that sync files between a folder on your device(s) and the cloud. Making it easy to backup and access your files from anywhere. Up until a few weeks ago I was paying for premium plans for both Google Drive and Dropbox.