Describes something that is not primary or original, but derived from or secondary to something else. Often used in academic or formal contexts.
This issue is derivative and not part of the essential discussion.
派生的な効果も考慮する必要がある。
We also need to consider secondary effects.
副次的 means 'secondary' or 'subsidiary', often implying something accompanying the main thing, whereas 派生的 stresses derivation.
From 派生 (はせい, 'derivation') + 的 (てき, '-like, -al'). The word 派生 is composed of 派 (は, 'branch, faction') and 生 (せい, 'life, birth').