What is difference between ELR and EFR.....?

What is the difference between ELR and EFR and how they can be selected for different applications…?

ELR means earth leakage relay or earth leakage circuit breaker, and EFR means earth fault relay. Both are protective relays. ELR will prevent shocks from circuit and protect life and EFR will protect transformers from fault current.Most of the EFR are IDMT type relays ie Inverse Definite Minimum Time.