what is the diffirence between
.i'm in a hurry
The first says that you are going somewhere in a rush [possibly because you are late] or doing something in a rush.
I am in a hurry to get this parcel to the post office before it closes
The second says that you are doing something which you do not want to stop doing.
Sorry, I will not be able to come to the party tomorrow. I am busy moving house.