Custom Assessments are used for data collection and the names of the participants and their responses are known. An example of this would be a Learning Needs Assessment, where you can identify areas that you would like more training on, and your Staff Educator can see what it is that you would like to learn more about.
Surveys are used for data collection and the names of the participants and their specific responses are unknown (anonymous). Your Educator can see (as an example) that 40 people were invited to participate and 30 people actually did participate. The Educator cannot see who did and who didn’t, but could see the results of what the 30 completed surveys.