Yes, they are the same. A unique constraint in a table definition is exactly and precisely the same as an explicit unique index, save for what is different: - an explicit UNIQUE index may contain expressions, a UNIQUE constraint in a table may only contain bare columns - you have control over the identifier name of an explicit UNIQUE index but have no control over the identifier name of a unique index created by a unique constraint - you may drop or create an explicit UNIQUE index but you may not explicitly drop or create the index implicitly created by a UNIQUE constraint