Both subheadings require specific gravity below 0.94, but 390140 applies specifically to copolymers of ethylene with an alpha-olefin comonomer (such as butene, hexene, or octene) that do not meet the LDPE or LLDPE definitions in 390110. The distinction turns on the comonomer type and the resin's structural classification; a technical data sheet and, if necessary, a laboratory analysis of comonomer content are the standard documentation.

Several tariff lines under 3901 originating from China are subject to Section 301 measures. The measure applies at the 10-digit HTS line level, so importers should verify the specific line and current exclusion status rather than assuming the heading as a whole is or is not covered.