I used to save my Libreoffice Writer docs in the Save as type: Word 2007-2019. This is no longer available.
Thank you for your help!
I used to save my Libreoffice Writer docs in the Save as type: Word 2007-2019
… which isn’t a good idea, if using LibreOffice. You may want to read [Tutorial] Differences between Microsoft and AOO/LO files (View topic) • Apache OpenOffice Community Forum or search for the numerous questions/problems asked on this site, which are related to the use of foreign formats.
Word 365 means the special form of licence; you don’t buy but “rent” the application. And a Word template is a template, just like LibreOffice’s templates for Writer, but specified for Word. Hope I could help.
What is a template for Writer? See here: https://www.howtogeek.com/340277/how-to-make-libreoffice-writer-templates/
Why? I can’t tell you. 
“365” is a rolling-release name, which means we need not change the filter name each time MS decides to release a new version. That is the reason for the change.
Thank you, Mike. So if I understand you correctly…based on my prior Save as type of “Word 2007-2019 XML”, I should now probably use “Word 2007-365” if I want to continue as close as possible to my prior convention. Right?
Thanks again for your help, I appreciate it.
Phil
Even better. Thanks, Mike!