For .ipynb notebooks, I highly recommend using nbstripout [0] to strip the Jupiter output before committing the notebooks to the repository (thus making the diffs sane). You can also set it up as a 'filter', so it automatically runs before any git operations, whether it's add, commit, diff or an interactive rebase. [0] https://github.com/kynan/nbstripout
> thus making the diffs sane
You can also use ReviewNB [1] that is literally built for Jupyter notebook diffs. You can see notebook visual diffs for any commit or pull request on GitHub. For pull requests, you can also write comments on a notebook cell (emulating the typical code review experience for Jupyter notebooks)
Disclaimer: I built ReviewNB for Jupyter notebook code reviews on GitHub.