What are the similarities and differences of viroids and prions?

Viroids are small and infectious RNA molecules.  The term infectious means something to be negative... I think you can assume the rest of that part.  Prions are infectious protein particles, same term infectious.  They cause diseases in humans and animals.Viroids are small and infectious RNA molecules.  The term infectious means something to be negative... I think you can assume the rest of that part.  Prions are infectious protein particles, same term infectious. They cause diseases in humans and animals.

It's all just a search away, just google and summarize and there you go. :P

VIROIDS and PRIONS are both acellular pathogens, meaning that they: 

- Are not made of cells 
- Cannot reproduce on their own 
- Do not grow or undergo division 
- Do not transform energy 
- Lack machinery for protein synthesis 
- Are so small that they can only be seen with an electron microscope 

They are not within any kingdom and carry their own significant characteristics: 

1. Obligate intracellular parasite – require a host to cause damage 
2. Filterable – small enough to be filtrated 
3. Contains an outer protein coat and inner genome 
4. Has only 1 kind of nucleic acid (RNA or DNA, but never both) 
5. Lacks metabolic abilities

VIROIDS are very small, circular RNA (may appear linear), and infectious in plants. They do not contain a capsid. 

PRIONS are proteinaceous infective particles. Prions do not contain nucleic acid. Prions contain a single protein called PrP. The sequence of amino acid that makes up PrP can fold into at least an alpha-helices, cellular PrP and a disease causing form called beta-pleated sheets called prion PrP. All mammals have PrP.

Hoped I helped!