What is EcoRI ? How does EcoRI differ form an exonuclease ?

Explanation

EcoRI is a restriction endonuclease, obtained from an E.Coil bacterium.
The convention for naming these enzymes is the first letter of the name comes from the genes and the second two letters comes from the species of prokaryotic cell from which they were isolated, e.g. EcoRI exonuclease removes nucleotides from the ends of the DNA. While the EcoRI makes cuts at specific positions within the DNA.