The difference is slight, but detectable, although you may expect disagreements among speakers in matters like this. According to my own (non-native) intuition, "Don´t hurry" is right when you want to tell your interlocutor to do something rightaway but in a leisurely (hence, relaxed, safe, reliable) way. "Don´t be in a hurry [to do X]" rather sugests "take things easy", "let this matter cool down", "think over this course of action and possible alternatives before embarking on X", "do not rush into doing X (as I cannot assure you it is the best course of action open to you). In other words, the former tells you to do something rightaway, but without running any risks for reasons of speed; the second tells you NOT to do X before thinking carefully about whether doing X is the most sensible course of action in the circumstances. :-)

These are both complete ideas. Do not hurry... Take your time, I can wait. I do not mind that at all. Do not be in a hurry... I want you to do this task well, not fast. I am more interested in quality than speed with this project I have you doing.

i think “don't hurry ” needs some words after it or dependent something like that ex) Don't hurry your wedding. while “don't be in a hurry” can just stay by itself or independent you use this phrase(is this a sentence i'm not sure) to tell/ask or to keep something from being in a hurry. *sorry, i'm really not a good at explaining stuff ^^