Question: how bcnf is different from 3nf?
Answer: BCNF is a normal form in which for every one of a table's non-trivial functional dependencies, is a superkey; 3NF is normal form in which the table is in 2NF and every non-prime attribute is non-transitively dependent on every key in the table. 3NF is the Third normal form used in relational database normalization.