A freestone is a river that forms from snowmelt in mountains. This snowmelt forms into small creek which flow downwards. These small creek change into streams and eventually form into a river and over a distance tributaries immerse into main river. On early stage a freestone river is called the headwaters. In the spring and summer, freestones offer great fishing but in winter headwaters may get freeze. Freestone river is fishaible though, but it depends on weather and seasons also.
A tailwater begins at a dam. In other words a freestone may flow into a reservoir, but when it then comes out the dam, it becomes a tailwater. Generally, when it comes over the top, water is warm and when it comes out the bottom water is cold. A tailwater is rich in fishes, so almost throughout the year it is good for fishing.