As far as the differences in power and distortion go, assuming that they are perfectly accurate, it is totally trivial. You will not hear any difference in distortion between
0.04% and
0.08% THD (the rated difference is greater than you say, but still trivial). Also, for power, it takes a doubling of power to make just a 3dB difference, which is slight, but clearly audible. To get 3dB above the 80 watts of the Marantz, it would take 160 watts. The difference between 80 watts and 100 watts is probably not going to be noticed. Of course, this does not mean that they are both equal, as one may be better with lower impedances or whatever, and that could, in the right circumstances (i.e., with difficult speakers), matter. But the differences in these specifications themselves are insignificant.