Difference in Master-Detail relationship and look up relationship – Salesforce Interview question

One important question may asked in Salesforce interview is that what is difference in Master – Detail Relationship and Lookup relationship Fields.

Master – Detail Relationship :

1. We cannot create master – detail relationship type fields directly if records already exists. Instead we have to first create Look up fields then fill all the records with that lookup filed. After that we can convert the lookup fields to master – detail relationship.
2. If we delete master records then detail (Child) records are deleted.
3. It creates the parent(master) child(Detail) relationship between objects.

Look up relationship :

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

NOTE : The field conversion can only done between master detail relationship and look up relationship, both controls type can interchanged by them only.