This isn't a complete analysis. From the same site, cast iron has a density of 6800-7800 kg/m³, whereas aluminium is around 2700 kg/m³: https://www.engineeringtoolbox.com/metal-alloys-densities-d_....

With specific heats of 0.91 kcal/(kg⋅K) for aluminium and 0.46 kcal/(kg⋅K) for cast iron, this works out to

Aluminium: ~2500 kcal/(kg⋅m³)

Cast iron: ~3100 - 3600 kcal/(kg⋅m³)

So for a pan of the same thickness/shape, cast iron should have a heat capacity that's 25-45% higher.