What is the difference between a convergent boundary and subduction?
All subduction boundaries are convergent boundaries but not all convergent boundaries are subduction zones.
A subduction zone is where an ocean crust meets a continental crust. The ocean crust is pushed under the continental crust creating a subduction zone and a deep ocean trench. This is a converging boundary.
There is also the possibility of an ocean crust connected to a continental crust meeting another ocean crust causing both to dive down. The Marianna's trench is an example of this type of converging boundary. It is also an example of a subduction zone.
There are other types of converging boundaries. Where the Indian plate a continental crust meets the Asian plate also a continental crust, the highest mountains in the world result the Himalaya. Instead of one plate diving under the other creating a subduction zone, both plates buckle upwards. Along the coast of California two plates meet at an angle causing a transverse fault. This created the famous San Andras fault. This is another type of a converging boundary.
So subduction zones are always the result of a converging boundary. But here are other converging boundaries that do not result in a subduction zone.