how to use octovis in Ros Melodic

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Thanks for Solrac3589 for his answer to my post which help me to run octomap server according to my PointCloud2 data and i have subscribed to occupied_cells_vis in Rviz, but i get confused about octovis, i have installed octovis using sudo install ros-melodic-octovis, can any one -please- give ma a short explanation about the octovis, is it similar to octomap_server, or it is just like a Rviz, what is the benefit of using it