Days of Protest
Both images allude to the situation occuring in between the November 17th Massacre and the November 27th General Strike.
In the second image however, which occured on the 21st, shows people who appear to be more jubilant and euphoric. Earlier on in the revolutionary effort, people were much more carefree, drunk on the new freedoms they had after 20 years of silence. This happy atmosphere faded over the course of the 10 days however, as people began to remember that they needed to keep fighting. The second image therefore appears more solemn compared to the first. There are no smiles, and each person features appears almost as if they are quiet.
It's notable that in the first image, Havel is not above the other people as he is in the second one, which occured days earlier. He never did consider himself a leader however, which may explain the first photo as the days of the revolution wear on.