If you share your lists with someone, you may notice that sometimes a blue dot appears in the upper right corner of the lists icon:
It means that as a result of the last synchronisation the content of the other lists (not the one you are currently viewing) has got changed.
Apart from that, a blue dot appears in the list of lists next to the lists' titles that contain the changes:
If you open such a list, you will see blue dots next to the names of the changed/added products:
This feature lets you avoid missing a new list of products and the updates in your lists.