These terms are pretty well defined by now.
"troposphere: 1. The lower layers of atmosphere, in which the change of temperature with height is relatively large. It is the region where clouds form, convection is active, and mixing is continuous and more or less complete. [JP1] 2. The layer of the Earth's atmosphere, between the surface and the stratosphere, in which temperature decreases with altitude and which contains approximately 80% of the total air mass. (188) Note: The thickness of the troposphere varies with season and latitude. It is usually 16 km to 18 km thick over tropical regions, and less than 10 km thick over the poles."
I couldn't find an equivalently detailed definition for stratosphere, but one way to define it is the area of the atmosphere where the temperature increases with altitude, rather than decreases.