A test report is a laboratory's record of sample test data, proving that "this particular sample passed these items"; a certificate is a conformity determination made by a certification body according to rules regarding a product/system, usually accompanied by factory inspection and ongoing surveillance. The former is evidence, the latter is a conclusion. The CE system is mainly based on reports + technical documentation + DoC, and in most cases does not issue a "certificate"; FCC ID, NB type testing, and national COC are true certificates.
During procurement and platform review, for reports check "whether the items are complete, whether the standards are current, and the laboratory's qualifications"; for certificates check "whether the issuing body is on the authorized list." Neither can prove compliance on its own; supporting documents are required.