What is the difference between CHECK and CONSTRAINT CHECK? is there any difference between the follow exemples?

ProjNum int 
    CONSTRAINT nn_ProjNum NOT NULL 
        CONSTRAINT C_ProjNum CHECK (ProjNum &gt;= 10)


and

ProjNum int NOT NULL 
    CHECK (ProjNum &gt;= 10)


Thanks.
There is no difference in SQL Server between those two statements. Each results in NOT NULL column (not a constraint) with a single check constraint. The only difference is that second one creates a system-named check constraint, something like 'CK__t__ProjNum__4AB81AF0'.