Now here are some examples: 你急急忙忙的要去干什么？You are so hurry! What are you going to do? 他慌慌张张的样子很是可疑。He is very doubtful，because he behave 慌慌张张 他急忙拿出电话来，给他老婆打了个电话。【急忙=hurry】 He hurried to pick up his telephone and made a call to his wife 他很慌张，说话磕磕绊绊的 ----------------------- 慌张： 一般是做了不好的事情之后 匆忙：为了赶时间

急急忙忙重点在动作{action}，慌慌张张重点在心理活动{mental activity}

急急忙忙，is more like talking about the ACTION (as you said very quickly, at top speed) in hurry. 慌慌张张，emphasize on the EMOTION of being in hurry. If some one say his heart beats faster in a hurry, and his face looks very worry or nervous , running around but don't know what to do then we can say he is 慌慌张张。

The main difference between the two words：The emphas of the word "急急忙忙" is " urgent",The emphas of the word "慌慌张张" is" panic”

1.急急忙忙和慌慌张张一般用于形容词，比如说：你不要慌慌张张的，慢慢来。（ps.我们一般多用慌慌张张而不是急急忙忙）which means ,Don't be hurry ,slow it down. 2.急忙 means very hurry,一般是副词的用法，比如说：他急忙地走了。 3.慌张 means be in a hurry and feel nervous about something ,更多的表示一种心情。一般说：他神色慌张的跑了。He ran flustered。 希望我的回答对你能够有帮助。