Amazon waited until the dust settled from last week’s news to launch Amazon Cloud Drive for Mac and Windows. Dropbox and Microsoft SkyDrive each got major updates last week, and the mythical Google Drive launched, too. What’s the difference between all these clouds and drives, anyway?

There’s a pretty big difference between Amazon Cloud Drive and the rest. You can think of Dropbox, Google Drive and Microsoft SkyDrive as the “magic folder” model. They all have a folder on your computer that works just like any other, except the contents of the folder are kept in sync with the cloud, so you can access that folder from other places.

Amazon Cloud Drive is different. It works more like a locker. You copy files and folders onto it for storage in the cloud, and you can copy them back down. So instead of just syncing automatically, Amazon Cloud Drive is for sending things back and forth.

For that reason, you can’t use Amazon Cloud Drive like you can the others, as a way to find and use your cloud-hosted files just like you would anything else on your computer. But it is useful for inexpensive storage, if you want to move stuff off of your local hard drive. It will also store and play your music through the Web interface from any device.

But Amazon Cloud Drive isn’t in the same league as Dropbox, Google Drive or Microsoft SkyDrive. If you want synced files you can work on, use those. But if you’re just looking for a cheap way to store a bunch of files in the cloud, Amazon’s offering might be what you’re looking for, and the new desktop clients for it are free.

jon mitchell