OneDrive Files
OneDrive for Business is a place where you can store files from your computer into the cloud, and access them from any device, or share them with others.
As part of Office 365, OneDrive lets you update and share your files from anywhere and work on Office documents with others at the same time. Think of OneDrive as your own individual workspace.
If you leave the organisation files in your OneDrive account (even if they are shared with other people) will be deleted (typically a year after your account is closed).
Teams Files
Teams is a communication and collaboration tool that allows multiple individuals and teams to work on documents and projects at the same time. Teams allows you to communicate and collaborate on documents with both internal and external users and teams.
Importantly, if you store files in a Team then the files belong to the team, rather than an individual. This is useful if important files are shared with other users