There are only seven derived SI units (e.g. length, m) while a fundamental SI unit is a combination of two or more base SI units (e.g. speed, m/s).

A derived SI unit is a combination of two or more base SI units (e.g. speed, m/s) while there are only seven fundamental SI units (e.g. length, m).

A derived SI unit is another term for a fundamental SI unit.