dates...
I started using MS Word for Mac 1.05 in 1985, with the menu system. On DOS-based systems I used Word Perfect; on CP/M I used WordStar. WinWord stunk up the place, and Windows 1 and 2 were worse. Excel 1 also arrived in 1985. PowerPoint had not yet been purchased and renamed, and Access had not been perpetuated yet. Fast-forward to 2007, 22 (not, repeat, NOT 25) years later I was using Office 2004 and 2008 on Mac, and 2003 and 2007 on Windows. I kept Office 2004 and 2003 around for a while, as Office 2008 had numerous bugs. (no ribbon, though.) If, for example, I wanted to move a PowerPoint from Office 2007 to a Mac, I had to either save it as a PPT, and run it past Office 2004 before opening it in Office 2008 (yes, really, roughly 25% of my PowerPoints wouldn't work if I just opened them in Office 2008, Microsoft wasn't compatible with Microsoft, imagine that) or I had to install the add-on which let Office 2003 read Office 2007 files and send them on. This joyous state of affairs persisted until Office 2010/2011, which could read/write each others' files. Office 2011 had the beginnings of a ribbon. Being a Mac system, it also had menus. The ribbon was markedly different. Office 2013 arrived. No Mac version did. Office 2016 for Windows and (be still my heart!) 2016 for Mac, not a different version number! arrived and Office for Mac still had menus, and still only kinda-sorta had a ribbon. The files could be round-tripped without having to jump behind God's back, though.
It should be noted that command (not control...) key combinations which worked for Word and Excel in 1985 still do, with one or two exceptions (command-h has been liberated by the OS)