There are more than 100 species of coniferous and more than 50 of deciduous woods in North America. Woods vary widely in colour, grain pattern and physical properties from species to species - even tree to tree. Trees that grow at higher altitudes, in harsher climates grow more slowly and are harder, darker and denser than those in valley bottoms.
Within the log, boards will vary as well. In sawmills, boards will often be cut in specific orientations for either grain pattern or strength.