What is the difference between an analytical standard and a certified reference material?
An analytical standard is a compound of suitable purity and known concentration to be used as a calibration standard for an assay.

A certified reference material is a material which has been certified by some trusted organisation to be of a consistent quality and composition. Normally, but not always, the concentrations of the major components of a CRM have been carefully measured. For example, the US-NIST produce hundreds of reference materials for everything from limestone to baking chocolate to dried human lung tissue. Labs analysing these materials use the reference material as a quality control to check that they are consistent with other labs.