What is the difference between a directed and undirected graph

Question

What is the difference between these fundamental types?

In drawings I see that the directed has arrows, but what exactly is meant by these arrows in the directed graph a

Answer 1

In a directed graph, there is direction but in un-directed graph there is no direction.

Think in in terms of city network , where City A-> City B represents one way from City A to City B which means you can travel from City A to City B (may be through this path). It's an example of directed graph City c - City D represents the un-directed graph where you can travel in any direction