Deployments for sandbox systems exclude some applications. This type of deployment takes place at the same time as production so the two systems are always up-to-date.
Sandbox and Beta systems are eligible for this service.
More Information: Sandbox Deployments
The Developer Instance is available for beta systems and include all applications. This type of deployment is designed for staggered deployments in which the Beta system receives updates in advance of the production system.
More Information: Developer Deployments