Throughout the evolution of IT differing methodologies, technologies, and frameworks have evolved at different rates, and sometimes in different directions. The most recent revisions of frameworks such as ITIL, Agile, and PMP have brought these frameworks closer to alignment, but they're not fully there yet.
Release and Deployment are 2 separate words that have traditionally been used together to form a single process step. Organisations have been left to then define exactly what "release & deployment" means for their organisation.
In response to industry requests for clarification, recent evolutions of frameworks have attempted to define the individual aspects of "release & deployment". This has left us with a slight disparity. The emphasis is still the same; organisations should define what every step in every process means to them and tailor them to fit.
Try not to think of any of these as a right or wrong way to view a process step and consider that the organisation should define what happens in each step and ensure that each step is relevant to the goals of the process.