以后 vs 的时候 (after vs when)

After it, or during it?

• Both mark time — but one is "after", one is "when".
• …after以后yǐ hòu = "after (X happens)".
• …(of / 's)的detime时候shí hòu = "when / while (X is happening)".

…after以后yǐ hòu = after

• to finish class下课xià kèafter以后yǐ hòu = "after class"; variant of 吃吃chīto finish完wánafter以后yǐ hòu = "after finishing eating".

finish class下课xià kèafter以后yǐ hòu，I我wǒgo home回家huí jiā。

• to finish class下课xià kèafter以后yǐ hòu，I / me我wǒto return home回家huí jiā = "after class, I go home."

…(of / 's)的detime时候shí hòu = when / while

• to have a meal吃饭chī fàn(of / 's)的detime时候shí hòudon't别biéto speak说话shuō huà = "don't talk while eating."

eat吃饭chī fànwhen的时候de shí hou，don't别biétalk说话shuō huà。

• to have a meal吃饭chī fàn(of / 's)的detime时候shí hòudon't别biéto speak说话shuō huà = "don't talk while eating."

Recap

Read the full reference: HSK 4 grammar — Comparing similar time words.