I always thought the Wikipedia progress animations illustrated the difference between A*[1] and Dijkstra's[2] nicely (and see some variations compared[3]).

[1]: https://en.wikipedia.org/wiki/File:Astar_progress_animation....

[2]: https://upload.wikimedia.org/wikipedia/commons/2/23/Dijkstra...

[3]: https://en.wikipedia.org/wiki/User:Subh83/CommonsContrib#Ani...