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Hello G.,First: The differences are the the content, and the size...
Then: It depends of the usage... ; You can use:
If you want to use instead the internal layout (Smetana or ELK) to produce the diagram which normally use Graphviz (e.g. usecase diagrams, class diagrams, object diagrams, component diagrams, deployment diagram, state diagrams and Legacy activity diagrams)
See doc. here:
If that can help,Regards,Th.