Explode vs. Implode

Take a plastic bottle. Fill it with water until it is full. Continue filling it with water - plastic will expand, stretch, and eventually burst. This is an explosion, an outward expansion.

Now take same bottle, and suck air out of it. Keep sucking air out, creating vacuum, and pulling sides of the bottle inside. The bottle is experiencing an implosion, an inward expansion.

To add to this - if you EXplode a building, debris ends up everywhere - spread out for many yards/meters. If you IMplode a building, 99% of the debris falls into the footprint of the building.