A townhome/condo could be a "fee-simple" property or part of a common community with shared ownership. The fee-simple means you own the dirt below and sky above...look for the legal description that includes lot, block and section number. The other type is where you are a percentage owner of the entire community, and your part is within the 4 walls of unit "x". Having a garage, one or two story, touching walls etc has no bearing on the legal description of a "townhome".
Both types could have common walls, both types could have monthly assocation dues, both types could have very little insurance paid by the HOA all the way to full coverage paid by the HOA, some units you are in charge of exterior maintance and others the HOA takes care of everything.
Financing is typically easier on a fee-simple property, but in Houston, those are typically in higher price ranges. Non fee simple would likely require the community to be at a minumum 51% owner occupied before you can do FHA financing or a loan with 5% down.
Get with a Realtor who has sold these types of properties and can give you more detailed advise. Both are good to purchase, just don't overpay and stay put for 5-10 years and you will come out ahead when you sell.