3-4-1-2 To 3-4-2-1 Transition: Tactical shifts, Player adjustments, Advantages

What are the key tactical shifts when transitioning from 3-4-1-2 to 3-4-2-1?

How do player responsibilities change in the 3-4-2-1 formation?

What advantages does the 3-4-2-1 formation offer over 3-4-1-2?

What are the disadvantages of switching to 3-4-2-1?