Google Workspace is just your own instances of their services running on their servers for you. You manage it as your own domain and it has all the services you get with a with GMail account, including Google Docs. It was called G Suite before. I don't know what Google One is.
[edit: "Google One replaced the paid services of Google Drive." Apparently Workspaces is for businesses and Google One is for consumers. It seems that you can't use your own domain as a consumer.]
This is odd. When "migrating" from G-Suite to Workspaces a couple of days ago I got the option to continue as not-a-company. I migrated a company account but still have a personal account with a domain to migrate. I'm sensing problems ahead...
I don't know honestly. I tried asking about exactly this on Community but they just wanted to gaslight me about it being a valid question and then deleted the thread to hide the evidence of that embarrassment. I did a Google Takeout and moved all my stuff to Proton and whatnot.
[edit: "Google One replaced the paid services of Google Drive." Apparently Workspaces is for businesses and Google One is for consumers. It seems that you can't use your own domain as a consumer.]