OneDrive is Microsoft's personal cloud storage and sync service that lets you access your files from any device. Whereas OneDrive for Business is the same service but for company use only. After you sign in to OneDrive on your computer, you'll see a dedicated OneDrive folder, everything you put there is synced with Microsoft servers. In addition, you can map OneDrive as network drive with the help of cloud managers like CloudMounter and have access to your online files right from Finder.