What is the main difference between second normal form and third normal form?

Question

Database design

Having shoveled 1.5 pages of search results, I came to the conclusion that both there and there, NOT the key attributes of the table should depend only on the Primary key. The only difference that I caught between them is that in 2nf a non-key attribute is irreducibly dependent on PK, and in 3nf the same non-key attribute is non-transitively dependent on PK. The difference is quite insignificant. Maybe I missed something, help me figure it out, eh?

Answer 1

The second form eliminates the dependence of non-key fields on part of the key.
Third normal form excludes non-key fields from being dependent on other non-key fields.