Earthenware

A porous clay body which is often waterproofed by a covering glaze. 

The simplest division of all pottery is into earthenware and stoneware; the dividing criterion being the porosity of the fired body. If the porosity of the fired body is more than 5%, then it is earthenware. 

Earthenware is often fired below 2012°F (1100°C).  The lower firing temperature of earthenware is also a defining characteristic.

Scource:

Vitrify

High-fire clay bodies become vitrified at peak temperature, as the result of the fluxing of feldspathoids and free silica.  In the vitrified clay, the particles are welded together in a glassy matrix, characterized by a low porosity. 

Porcelain is a clay which vitrifies more than most, as displayed by its glassy, almost translucent appearance.

Source:

The Potter's Dictionary of Materials and Techniques, Frank and Janet Hamer, 1986 A and C Black Publishers ltd. NY, NY

This article could use some history.

Porcelain

A vitrified white and translucent clay body, usually fired to temeratures above 2336°F (cone 9). 

Stoneware

Stoneware is a type of clay fired to a temperature usually above 2192 °F (1200 °C) at which point it becomes vitrified.

Stoneware is dense, strong,  and often grey or brownish in color due to its characteristic non-hemogenous makeup of variously sized particles of clay, grog, sand ect.   For this reason porcelain is usually not considered to be a stoneware. 

Stoke

(Verb) The act of putting a quantity of wood in the kiln, either in the main firebox or on the sidestokes. (noun) Any amount of wood that has been put into the kiln at one discrete time.