Not necessarily. For instance, Palm Springs is in the LA broadcast market. So, accessing Locast from PS will give you the LA stations, not the PS/Riverside channels that are available via antenna.
As another data point, while I am technically within 20–30 miles of the LA broadcast towers, I cannot easily receive the channels, even with a large chimney–mounted antenna. My house is in the lee of foothills that sit between my house and the towers, impeding reception.