Canary channel: Canary builds are the bleeding edge, released about weekly. While these builds do get tested, they are still subject to bugs, as we want people to see what's new as soon as possible. This is not recommended for production.
Dev channel: Dev builds are hand-picked older canary builds that survived the test of time. It should be updated roughly bi-weekly or monthly.
Beta channel: Not used yet. This will be used when we'll have beta-quality releases. Right now Android Studio is considered preview-quality.
Stable channel: Not used yet. That will be for version 1.0 and following stable milestones.