Comments can be made in two different types, a standard comment and a note. Notes are defined by a blue border to clearly distinguish between the two.
The main difference between a note and a comment is the way they are presented in the App. As the two types of comments are distinguishable, you can utilise this to create your own system for when to use each type. For example you could utilise comments as a way to communicate within your team and then use notes for specific comments that you wish to pull into your Data Studio report. Therefore, separating internal comments from Client or stakeholder facing reports.