after did sth.和after doing sth.的区别在于：
一，after的词性不同
1. after sb. did sth. 其实应该是after后面接了一个完整的句子，所以after是连词；
2. after doing sth，是一个介宾短语，after是介词，后面接了动名词形式；
二，时态可以不同
after sb. did sth.是一般过去时，所以前面或者后面的主句应该也是过去式；例如：
After she died I felt very, very upset.
她死后，我感觉非常非常难过。
He spent six weeks in traction after he broke his leg.
他腿部骨折后做了六个星期的牵引治疗。
After he won the amateur championship he turned professional.
他获得业余赛冠军后就转为职业运动员了。
2. after doing sth所在的句子时态不是固定的，可以是过去式、现在时、将来时等等。例如：
She began to play piano after finishing her homework.
做完作业后，她开始弹钢琴。
I feel so much better after talking to you.
和你交谈后我感觉好多了。
Reapply sunscreen hourly and after swimming.
每小时以及游泳后重新抹一次防晒霜。