Good Day, Ms. Liu!
Kevin Keenan here ... I just responded to your e-mail when I noticed your "follow-up" question ... The response provided by Mr. Don Tepper is the best of what I read to which I would add, there is almost ALWAYS an "Association Fee" that is associated with a Condominium or Townhome which pays for the maintenance of "Common Areas" such as those mentioned (i.e. Lobbies and Elevators) as well as Pools, Tennis Courts, Parking Lots, Interior Roads, Landscaping, etc.) There are typically NO such fees with an apartment to the Tenant - as these are paid by the Owner - and in the case of a Single Family Residence, ALL maintenance costs are the responsibility of the Owner.
A townhouse describes a physical structure. Usually, it's one of a string of buildings with common walls. Often, they're 2 or 3 stories tall. There's an end unit, then several interior units, then another end unit.
A single-family home describes a physical structure. It is a stand-alone home, on a piece of ground, with windows on all sides.
A condo describes a legal structure, not a physical structure. Condos often (but not always) are units in a multi-unit building. In a condo, you own everything inside the four walls. Plus you and the other owners jointly own the "common elements" such as the lobby and elevator. Note: Because a condo is a legal structure, it can also describe townhouses and even single-family homes. You can have a townhouse complex that's really condos.
An apartment describes a physical structure. It's a building with 2 or more units owned by someone else. People who live there are tenants. They rent, not own.
I hope this helps and know that if you have any further questions, Ms. Liu, feel welcome to contact me anytime!
Kevin Keenan, MBA, GRI, SFR
Broker / Owner
Millennium K2 Realty
4410 East Casselle Avenue
Orange, CA 92869