The most salient difference is that CARD requires a license for commercial use, while AMRFinderPlus is Public. However, according to a recent benchmark (https://www.medrxiv.org/content/10.1101/2022.08.11.22278689v2.full) you are probably better off with ARDaP.

Note especially this from the benchmark: "Due to its inability to predict AMR towards individual antibiotics, and a very high rate of false-positive predictions in the Global Dataset, CARD was deemed unsuitable for P. aeruginosa AMR analysis and was excluded from further assessment"

CARD is somewhat nicer because it's hand-curated and organized; but it's not really a substitute for a dedicated AMR finding and scoring tool.