They are understood to be so although I haven't attempted to open files from one to the other.
I used Excel at work which hung up at times and this is not anything I have encountered with AOO.
No harm in trying though !
Like apparently some functions which were for free will no longer be so with Windows 10 - suggestion I have heard is do not accept their 'free' upgrade.
Download 'Apache Open Office' for free which does everything which MS Office does but better.
I have used it for eight years or more and is a complete suite.