Difference between Primary Key and unique key ?

Difference between Primary Key and unique key ?
Ans)
Primary Key Restrict duplicate values and null values each table can have only one primary key,default clustered index is the primary key.

unique key restrict duplicate values and allow only one null value. default non clustered index is an unique key
Difference between Primary Key and unique key ?
Ans)
Primary Key Restrict duplicate values and null values each table can have only one primary key,default clustered index is the primary key.

unique key restrict duplicate values and allow only one null value. default non clustered index is an unique key