Well, at first we were totally confused too. So here is an explanation of sorts....I think there is an old post on this too...but anyway...will write about it again.
First you have the 'Detached House'. This is a house that is completely separate from the other homes around and has no common wall. You have space on all sides, your own little lawn in front with a driveway and garage, and a lawn behind with some walking space on the two sides. Don't be fooled though. Just because a house is detached, it doesn't mean that it is bigger than the semi-detached or townhouse. Always check the square footage of the actual living space and not just the lot size. (Plot size)