Audit criteria represents set of requirements against which you will perform the audit. In case of internal audit or certification audit, the criteria is the standard and relevant management system documentation, for example is the production process conducted according to production procedure. Other criteria can be requirements of the customers, legal requirements, etc. For more information, see: What is the ISO 9001 audit program, and how does it work? https://advisera.com/9001academy/blog/2017/01/24/what-is-the-iso-9001-audit-program-and-how-does-it-work/
Evidence-based approach means that you are basing your decision or judgement on evidence you've collected. For example, if you want to determine whether the organization has conducted training according to the training program it developed, you will look for the training records.