diff

Trick is to convert document into text files and make diff on it.

sudo apt-get install odt2txt docx2txt
git config --global diff.odf.textconv "odt2txt"
git config --global diff.word.textconv "docx2txt"

Create file ~/.config/git/attributes and put following lines into it:

~/.config/git/attributes

*.ods diff=odf
*.odt diff=odf
*.odp diff=odf
*.docx diff=word

Test if it working. Go to your git repository working copy:

git log -p some_document.odt

Instead of

Binary files a/some_document.odt and b/some_document.odt differ

you should see normal text diff.