Unfortunately, in Configuration Manager 2007, because of how and when specific features were implemented, we ended up with rather a confusing mix of terms. Distribution usually means "to send out", whereas "deployment" often includes more than this, for example, installation with configuration and customizations for the end user.
We addressed this in System Center 2012 Configuration Manager and standardized on using "distribute" when sending software to distribution points, and "deploy" when installing software on client computers. We tried to keep "install" for the product itself (running Setup, installing sites and site system roles, installing clients).