How are viroids different from viruses

OR

What is the difference between viroids and viruses?

Viroids are free RNA molecules of low molecular weight without any protein coat while viruses can have either RNA or DNA molecules encapsulated in a protein coat. Viroids are smaller in size than viruses. Viroids infect only plants whereas virus infects all types of organisms. In viroids, a protein coat is absent whereas in viruses a protein covering or a coat called a capsid is present around the genetic material.