Understanding benefit of higher watts on power bank
Capacity and wattage are certainly not the same - two batteries could both by 5000 mAh but one could be 12 volt and the other could be 1.5 volts. Clearly the 12 volt battery has 8 times the wattage capabilities on face value.

However, even this may not be true if you dug deeper. A 5000mAh battery may well be able to supply 10 amps for 30 minutes and this would be a bigger wattage than discharging at 5 amps but, a different battery not be be allowed to exceed 5 amp output despite having a 5000mAh rating.

Read the small print in the data sheet. Look at the discharge curves. Compare carefully. Decide on what you need carefully.