What is the difference between CRISPRi and RNAi?

Both CRISPR interference (CRISPRi) and RNA interference (RNAi) are common techniques for gene silencing. The major difference between these two methods is that CRISPRi represses genes at the DNA level, whereas RNAi controls genes at the mRNA level. In other words, CRISPRi regulates gene expression primarily by inhibiting gene transcription, while RNAi destroys RNA transcripts. Comparing to RNAi, CRISPRi is associated with higher efficiency, greater versatility and fewer off-target effect.