SaltStack (or Salt) is the tool that sends instructions and provisioning data from the 'salt-master', or the master server, to it's 'minions', or slave servers.
Salt-Cloud is the tool that allows you to automatically setup and provision the Salt software to cloud servers, such as Amazon or DigitalOcean. Salt-Cloud also automated the process of adding minions and the authentication and acceptance of keys on the master. Salt-Cloud is installed as part of Salt now, except on some RHEL systems (Fedora, CentOS) where Salt and Salt-Cloud are two separate installs.
By default everything is installed in:
/etc/salt