How does a plastic curry comb differ from a rubber curry comb?

The distinction between a plastic curry comb and a rubber curry comb primarily lies in their usage and the material properties of each type. Plastic curry combs are typically rigid and are designed to effectively groom a horse's coat during the dry grooming process. They are particularly useful for removing loose dirt, dust, and hair from the coat, making them ideal for daily grooming routines when the horse's coat is dry.

Conversely, rubber curry combs are softer and more flexible, allowing them to be more effective at massaging the horse’s skin and bringing dirt and loose hair to the surface, particularly when the horse is wet or during bathing. Thus, the characteristic of plastic curry combs being used mainly for dry grooming highlights the differences in their design and intended use, making this answer correct.