The term “Boards” typically refers to all materials that are 1x(one by) which typically measure approximately ¾” in thickness. The most common boards are 1x4 and 1x6 which are often used for trim. Lee Roy Jordan Lumber carries boards ranging from 1x2-1x12 and depending on the species they can be smooth four sides(S4S) or smooth one face and two edges(S1S2E).
“Dimensional lumber” is most often 2x(two by) material which if in the rough can measure a full 2 inches or sometimes 1 ¾” in thickness. 2x material that is surfaced four sides(S4S) usually measures 1 ½” thick. The most common dimension sizes are 2x4 and 2x6.