How rating scale is different from checklist?

You use a checklist to determine the completeness of something. For example, I use a checklist of all the materials that I use in my seminars and workshops. I keep the checklist to ensure that everything I need is available and ready.

You use a rating scale to determine the rating or level of something. For example, during my seminars I use a rating scale to determine the satisfaction rating of my participants, the appropriateness of the topics, the presentation delivery, and of the venue. Participants rate the seminar from 1 to 10. A rate of 1 would mean that they are not satisfied. A rate of 10 would mean that they are very delighted.