What is the difference between endonuclease and exonuclease?

Endonuclease – Nuclease that cleaves phosphoester bonds within a nucleic acid chain (It may be specific for RNA or for single-stranded or double-stranded DNA). exonuclease – Nuclease that cleaves phosphoester bonds one at a time from the end of a polynucleotide chain (It may be specific for either the 5′ or 3′ end of DNA or RNA).