Mwass is right.
The difference between a townhome and a condo is if you own the land that the home is on or not. If you are living in a townhome with the lot size of your unit being "common grounds" that usually means that you pay property taxes on your condo only. The taxes are based on an assessed value which is usually a reflection of the purchase price plus an inflatioary percentage per year unless improvements have been made. The land, if it is common grounds, is taxed and usually the association fee covers those taxes.