Infantry damage

Damage and strength depend on morale, from what I can see the first picture's morale is higher than the second one. Which means that the first army should be stronger than the second one.

The difference is that the 'mobilization' is different. One is 50% and the other is 100%. Mobilization can affect damage.

For more info, look at section 3.4.5 in this post [INDEX] Frequently Asked Questions

To add to that, mobilization starts of at 50% when the game starts, and it increases to 100% over a few days (i think 3 days if i remember correctly).