What is the difference between on error continue and on error propagate in Salesforce?

What is the difference between on error continue and on error propagate ? And in which situations we use them ?

• This discussion was modified 6 years, 8 months ago by  Gursimran Singh.
• This discussion was modified 6 years, 8 months ago by  Forcetalks.
• This discussion was modified 6 years, 8 months ago by  Forcetalks.