After Uploading a BOQ, you are able to save extra versions as you wish, press the three dots 🡪 Add new version 🡪 choose if you want to import the old BOQ or start afresh.

You can rename a version by pressing the three dots 🡪 version settings 🡪 enter your version name, (note that version number and date will be planted in the name automatically).
Now that you have at least two versions of BOQs, you can compare them by pressing the three dots 🡪 Version compare, the two will open on the same screen and you can easily analyse the differences between them (highlighted in orange), rows that appear in one version (green) and not the other (red).

If you have more than two versions, choose the two that are relevant for comparison: