Super volcanoes are much bigger than normal volcanoes, usually erupting at least 1000 cubic km of material in a single event and far less frequently than normal volcanoes. Normal volcanos erupt nearer to 1 cubic km of material. In addition it has a different shape in that it is sunk in the middle - in contrast to normal volcanoes, which have a peak.
There are a number of consequences of a super volcano eruption. A global consequence is the the ash is emitted into the atmosphere and can be carried by the wind to other countries where it may reduce sunlight and consequently in some cases, cause temperatures to fall - making it difficult to produce food through with increase crop failure. There may also be resulting deaths due to the lack of for production in certain areas of the world.