The main difference between these enzymes is that endonuclease cleave the phsphodiester bond in the polynucleotide present internal in the polynucleotide chain  whereas exonuclease cleave the phosphodiester bond from the ends

(I have googled it ,you can also watch the difference between these two on YouTube)

Hello Shraddha , Exonucleases are enzymes that cleave DNA sequences in a polynucleotide chain from either the 5' or 3' end one at a time. Exonuclease, like endonuclease, is a hydrolyzing enzyme that cleaves the phosphodiester bond between the nucleotides.

Hope it will be helpful for you :)