Yes. Unlike most other lanes, North America uses a stricter weight conversion:
1 RT = 1 CBM or approx. 363–375 KG (depending on carrier/forwarder).
Example:
Standard lane: 1 CBM = 1,000 KG
U.S./Canada lane: 1 CBM ≈ 363–375 KG
This means heavy cargo will be charged more RT on U.S./Canada lanes, making freight costlier than on other routes.