It's kinda both. To be clear, EUV directly refers to a specific type of lithography equipment, ones using extreme UV light sources. However, those changes come with a lot of changes in larger process flow that are all inter-related.

The change in EUV means smaller lithography lines, and also means needing photo resist, etching, cleaning, etc. - many other process steps, that support that size change. Add in that now, with EUV lithography, you are operating lithography under vacuum and its a huge challenge. Suddenly you have to have vacuum ready materials.

One of Intel's mid 2010 wins was getting immersion litho to work better than peers - similar thing just wet wafers rather than vacuum wafers.

EUV is a tool/technology, one used only on critical layers where that precision matters (e.g., gate patterning). But the larger (entire) manufacturing process has to be designed to enable the use of that tool/technology.