Fires behave differently in different terrains and with different availability of fuel.

Range fires that feed mainly on dry grass and low bushes can move with tremendous speed when they are being pushed by winds. The native americans knew this and understood that you can't outrun such a fire. Their tactic was to set another fire and then enter the burned-out area created by their blaze, so, when the bigger fire arrived they were in an 'island' without any fuel. I understand fire crews also use this tactic when it's necessary.

Fires in forests with steep up-and-down terrain tend to move more slowly on the down slope and more quickly on the up slope. They never move as fast as a range fire, unless the fire is "crowning", i.e. moving directly from treetop to treetop.

A "crown" fire moves fast and often creates its own fire storm, with locally fierce winds that drive the fire past all obstacles and send hot cinders high into the air for miles around, starting new blazes. These are considered the most dangerous fires of all.

But I'm not an expert by any stretch. I'm sure this information is out there on the web in much greater detail and from people with more knowledge and experience than I have.