Viruses and viroids differ in structure and the diseases they cause. How?
Viruses can have either RNA or DNA molecules enclosed in a protein coat, whereas viroids are free RNA molecules with low molecular weight and no protein coat. Viroids are smaller than viruses in size. Viruses infect only plants, but viroids infect all living things. Viroids lack a protein coat, whereas viruses have a protein covering or coat called capsid that surrounds the genetic material.
