The Micro Rounds are smaller round plains, the Macro are larger. Both can be used for a variety of things. You'll need to inject the injection morphs into them to make terrains, ie, mountains, craters, hills etc. I think RDNA still has a "small places" package for free for use with the micro planes.

As an example, you can use morphs or displacement on the planes, square or round to create bodies of water. The Macro would be good for the sea or ocean, stretching out to the horizon, the micro for a pond or lake.

Hope that helps.

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