What's the difference between Quick Render and Export?

Both are in the top bar of the editor. The difference is what you get and how fast.

Quick Render produces your clip fast and downloads it straight to your device. Use it when you want the file in your hands right now.

Export does the full render, producing the finished version ready to post — including publishing to your connected channels from within Zazu.

Which to use: Quick Render if you're grabbing a file to check on your phone or send to someone. Export for the version you'll actually publish.