costmap_2D vs SLAM

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I am trying to using move_base and a costmap to navigate a vehicle autonomously to a goal in an unknown map.

When looking at the costmap_2D wiki, I noticed that you can provide the node with sensor data and tfs, and it will build and update a costmap. We have successfully gotten this to work in simulation.

However, what is the difference between using this package to generate a costmap, and running SLAM algorithm like gmapping or cartographer? Thanks!