Checkpoint Node keeps track of the latest checkpoint in a directory that has same structure as that of NameNode’s directory. Checkpoint node creates checkpoints for the namespace at regular intervals by downloading the edits and fsimage file from the NameNode and merging it locally. The new image is then again updated back to the active NameNode.
Whereas Backup Node also providecheckpointingng functionality like that of the checkpoint node but it also maintains its up-to-date in-memory copy of the file system namespace that is in sync with the active NameNode.