One of the first things you learn when dealing with Division 06 (lumber) is that there are various different cuts related to wood. Each cut varies in price and advantages. For example, quarter cut wood is more expensive but provides greater stability in the wood (good for things like doors and tables). Flat sawn wood is more cost effective but has the potential to warp and doesn’t always have the grain pattern people are looking for.
I’ve summarized some resources which will walk you through the basics of lumber and the different types of wood.