Hmm...first set is strange all right. In both sets the white objects are liable to be sand dunes. The shadows in the second set suggest a canyon. The stuff that looks like vegetation/trees is likely to be just rough ground...maybe rocks. Just a guess, but the straigh edges in the first set could be controlled by faults or bedding...may be some kind of ground failure or structure-controlled erosion.

Can you email JPL and ask what is the interpretation?
Chris