Rough sawn (full dimensional) lumber.
2 inches x 4 inches x 96 inches (typically +100 inches).
Rough sawn lumber is larger than store bought S4S (surfaced “planed” 4 sides) lumber. Store bought “stud” lumber starts out as rough sawn lumber and is passed through a planer machine to smooth the four sides and it cut to 93 inches long.
Rough sawn lumber typically contains 51% more wood so please consider that when you are comparing prices.
Rough sawn 2x4x8ft (full dimensional) lumber has 5.3 board feet (bf). Store bought lumber has 3.5 bd ft.
A rough sawn board can be spaced every 24 inches, whereas store bought stud lumber should be every 16 inches. Over a span of 10 ft you can save on 3 boards. While the costs might be the same, you’re saving time in not having to put those other 3 boards in place.