再現 and 再発: recreating an earlier form and recurrence
Compare a model exhibit and efforts to recreate a flavor with recurring pain and a procedure review intended to prevent another accident.
Recreating a townscape or a flavor
昔の町並みを模型で再現した展示を、時間をかけて見学した。 reports taking time to view an exhibit that recreated an old townscape with models. 再現, read さいげん, concerns the exhibit's recreated scene; it does not say that the viewer made the models.
料理人は祖母の味を再現しようと、何度も調味料を変えた。 reports the chef repeatedly changing seasonings in an effort to recreate his grandmother's flavor. 再現しようと supplies the attempt, while changing the seasonings is the reported action. Successful recreation is not supplied.
Recurring pain and a prevention goal
治ったと思った痛みが翌月に再発した。 reports pain thought to have healed recurring the following month. 再発, read さいはつ, identifies its return; distinguish the earlier belief about healing from the later recurrence.
同じ事故の再発を防ぐため手順を見直した。 reports reviewing a procedure to prevent the same accident from recurring. The review took place, but preventing recurrence is its purpose rather than a supplied record of success.
What returns in each sentence
The model and cooking examples concern recreating an earlier appearance or flavor. The pain and accident examples concern a problem returning or an effort directed at preventing that return.
Do not collapse both words into an undifferentiated 'again.' Read the recreated exhibit, attempted flavor, recurring pain, and completed procedure review as their respective actions and results.
What differs between the exhibit with 再現 and the pain with 再発?
Show the answer and why
The exhibit recreates an earlier townscape with models. The pain returns after it was thought to have healed. Successful flavor recreation and successful prevention of another accident are not supplied.