LookUp vs Master - Detail relationship in SFDC

Master – Detail Relationship :

1. We cannot create master – detail relationship type fields directly if records already exists.
2. If we delete master records then detail (Child) records are deleted.
3. The Owner field on the detail and subdetail records is not available and is automatically set to the owner of the master record. Custom objects on the “detail” side of a master-detail relationship can't have sharing rules, manual sharing, or queues, as these require the Owner field.
4. You can define master-detail relationships between custom objects or between a custom object and a standard object. However, the standard object cannot be on the detail side of a relationship with a custom object. In addition, you cannot create a master-detail relationship in which the User or Lead objects are the master.
5. The master-detail relationship field is required on the page layout of the detail record.
6. Rollup Summary fields are only available on master-detail relationships, not lookups.
7. One detail side record can have maximum 2 masters but no limit on the Lookup fields.

Look up relationship :

1. Look up relationship creates relations between two objects.
2. If we delete any object then other object is not deleted.