Hi Sweta,
Master-Detail Relationship-
- You cannot have a detail record without a master.
- The detail record inherits sharing rules from the master.
- You cannot update the relationship to the master in a master-detail relationship.
- The number of master-detail relationships you can use are limited.
- You cannot set profile object permissions for a detail record
- Master-detail relationships are automatically included in report record types
LookUp Relationship –
- Lookups are generally for use where you may or may need to have a relationship between two objects (but not always).
- Lookups are generally used to reference commonly shared data, such as reference data.
- Lookups are used to link two objects together when you don’t want the behaviour of the master-detail – particularly around sharing rules, profile permissions and cascade delete.
- Lookups are used when you need to relate multiple ‘parents’ to the detail record.