Gaffer is a process management framework but also a set of command lines tools allowing you to manage on your machine or a cluster. All the command line tools are obviously using the framework.
Gaffer is an interface to the gaffer HTTP api and include support for loading/unloadin apps, scaling them up and down, ... . It can also be used as a manager for Procfile-based applications similar to foreman but using the gaffer framework. It is running your application directly using a Procfile or export it to a gafferd configuration file or simply to a JSON file that you could send to gafferd using the HTTP api.