Comparing "huifu" and "huanyuan"

This may be one of the trickiest two verbs to get right. 恢复 means to restore something that was destroyed and 还原 means returning something to it's original state.

恢复 can be used before the noun

恢复 expressing that something is restored that was once destroyed. messed up, or lost. It comes back into its original state or appearance. Often it is used with words like 身体, 体力, 社会, 秩序 etc.

One way to use 恢复 is to put it before the noun or noun phrase

恢复（了）+ Noun/Noun Phrase

Examples

• 恢复 体力。
• 中国 1977年 恢复 了 高考。
• 地铁 恢复 了 正常 运行。

恢复 can also be used at the end of a sentence

You can also put 恢复 after, usually paired with a 了.

Noun/Noun Phrase + 恢复了

Examples

• 他 的 身体 恢复 了。
• 社会 秩序 恢复 了。
• 他 的 职位 恢复 了 。

还原 emphasizes "restoring to original condition"

还原 also means "returning to the original state or condition", but this time it is strongly emphasizing going back exactly to how it was before. It does not have the same "destroyed" connotation of 恢复.

Grammar pattern wise, it's pretty much used the same way as 恢复.

还原 + Noun/Nominal Phrase

Examples

• 还原 历史 的 真相。
• 他 想 把 这个 应用程序 还原 成 代码。

Sources and further reading

Books

HSK6