Basically yes. Splunk does not refer to anything as an "agent" - that is terminology borrowed from other systems.
But, similar to an agent, a Splunk forwarder installs on many "client" systems (who may be "servers" themselves [web,ftp,mysql] , but they are not "servers" in the Splunk application sense).
Until 4.2, the same install package is used no matter what role a machine is playing (forwarder, indexer, search head). With 4.2, and the Universal forwarder, the packaging is much more like the traditional "server install" versus "agent install"