Both fall under mechanical wood pulp, but TMP uses steam-pressurized refining of wood chips, producing longer, stronger fibers than traditional stone groundwood. TMP is preferred for higher-quality newsprint and some specialty papers, while stone groundwood is used in lower-grade printing papers. The distinction matters for mill specifications but both are classified under the same trade heading.

Mechanical pulping is highly electricity-intensive, so producers in regions with low hydroelectric power costs — such as Canada and Scandinavia — hold a structural cost advantage. When energy prices spike in those regions, import prices rise accordingly, prompting US mills to evaluate furnish substitution or inventory build-up strategies.