How will it differ* To me 'the us of IDP in teaching' means that you are going to detail/document the process of using it in teaching. 'The practice of IDP in teaching' sounds like you are going to explain what IDP is and how you would use it , rather than documenting how you are/were using it. Hope this helps :)

i think its too tough because you cannot show your full interest on IPAD............

'The use of IDP' is what benefits IDP gives you when you use it. The first title would mean that the thesis examines how IDP can be used to aid teachers when they teach. 'The practice of IDP' is the act of using IDP, so if you were talking about the practice of IDP you would talk about how often and in what ways teachers use IDP. I assume IDP is some sort of teaching technique?