Explain the difference between a seamount and a volcanic island.

(This is science actually, I just chose something because I couldn't find science.)

I would expect them to be islands. As a volcano grows older the magma it releases would accumulate and solidify until the volcano was no longer below the water level. The longer a volcano is active the less likely it is to remain underwater due to this gradual build up.

An island is a landmass smaller than Greenland and surrounded by water on all its sides a seamount is an isolated step submarine volcanic feature less than 1000m high above sea floor