What's the difference between a JDM S15 Silvia Spec-R and a USDM 240SX?

The S15 Silvia Spec-R was JDM-only with the SR20DET turbo engine, 6-speed manual, and unique S15 bodywork. The USDM 240SX (S13/S14) came with the KA24DE or KA24E naturally-aspirated engine, lower power output, and no turbo option. JDM S15 Silvia imports are becoming eligible under the 25-year rule as of 2024.