Arcadium is purpose built for architecture - Sketchup isn't. This matters for basic objects like doors - you have to draw these in Sketchup and cut holes in walls - Arcadium they snap into place and just work - you can stretch them and move them and they auto resize automatically. And unlike the more complex and more expensive Revit, Autocad - the UI is far simpler to learn and understand. Arcadium is also a modern product so have a bunch of AI built in - eg photo to 3D model creation and AI rendering of views.