Magnolia 5.6 reached end of life on June 25, 2020. This branch is no longer supported, see End-of-life policy.
On the surface, both publishing and activation modules and the associated apps do the same thing: publish content from an author instance to a public instance:
The internals of this process are, however, different:
Base activation concepts remained unchanged. Transport layer is still using HTTP protocol. However new publishing implementation allows to easily plug in any type of transport layer.
The bundles in the 5.6 branch are shipped with publishing by default. If you are migrating from a pre-5.6 branch and intend to replace activation with publishing, see the Publishing vs Activation and custom commands section on the Upgrading to Magnolia 5.6.x page.