Mutations in RNA
Errors and mutations in DNA tend to be more severe than mutations in RNA.
These errors can occur during transcription, and may cause problems in the translation of proteins. The errors may also be due to mutations in the DNA.
RNA tends to be short lived (mRNA in mammalian cells exists for a maximum of a few days) so any mutated strands are quickly replaced.
Mutated RNA is also not replicated during cell division, so mutated strands are not passed to the next generation. Mutated DNA is maintained through cell division.