I’ve used Office 2003, 2007, 2010 etc. all the way up to 365 not for work purposes, but just happened to have interacted with all of the versions.
I have to say, I seriously don’t know what happened, but Office 2003-2007 feels the most stable and least clunky versions of Office (at least Word) in terms of basic word processing.
I learned how to properly edit and format text in Word in university in a way that I could, without fail, reproduce almost any text design you could think of. When I was learning it on Office 2007 I believe, everything was so stable and predictable. Now when somebody asks me to format some text with 365, the styles functionality continually keeps bugging out and doing stupid shit that I basically can’t recover from unless I create a blank file.
In conclusion, Office 2007 > 365
/rant
There’s Office online, which has a free tier and a “365” tier, whatever that means. Does it mean that you have Office available 365 days a year? Good luck on February 29th, I guess. /j
Anyway, Microsoft transitioned Office into a subscription-based model, which I abhor because I just want to have a piece of software without feature updates, just bug and security fixes. So Office 365 is just normal Office, but on a subscription basis.