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 do the same thing: publish content from an author instance to a public instance:
The internals of this process are, however, different:
Activation module has been refactored and split into multiple modules.
Driving reason for the activation rewrite was to split activation into set of maintanable and extensible components. Another reason was to remove deprecated code usages.
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.