Difference maps between the Planck 30 GHz and WMAP K-band maps. The columns are (1) Planck 2018 vs. WMAP9, (2) Planck PR4 vs. WMAP9, (3) BEYONDPLANCK vs. WMAP9, and (4) COSMOGLOBEPlanck 30 GHz and WMAP K-band both produced in this paper. All maps have been smoothed to a common resolution of 2° FWHM, and the K-band map has been scaled by 0.495 to account for different central frequencies, assuming a synchrotron spectral index β_s = −3.1.