Yes, that's exactly what it is. The "data" might be 8K textures, as part of the binarization it gets converted into a format that the client can understand, but also follows a "recipe" for the texture set throught the editor(so convert it a 2K texture with a specific colour spec). Same for models etc.
And yes, the client itself usually can't read the raw data, and even if it could there is not enough ram on consoles to load everything as-is. The workstations we use for development all have 128GB of ram just so you can load the map and all models in-editor.
And yes, the client itself usually can't read the raw data, and even if it could there is not enough ram on consoles to load everything as-is. The workstations we use for development all have 128GB of ram just so you can load the map and all models in-editor.