Final answer:
A crook in lumber refers to a sideways curvature or bow in the board, while a crown refers to the center of the board being higher than the edges, creating a curve or arch.
Step-by-step explanation:
Woodworking: Lumber Defects
A crook in lumber refers to a defect where the board is not straight along its length. It typically appears as a sideways curvature or bow in the board. This defect can make the board difficult to use for certain applications, as it may not fit properly or cause stability issues.
On the other hand, when the term 'crown' is used in relation to lumber, it refers to a defect where the board is not flat across its width. Instead, the center of the board is higher than the edges, creating a curve or arch. This defect can affect the stability and usability of the board, especially in applications where a flat surface is required.