Although I'm not a computer science engineer, I'll make an attempt at the answer. Others, please correct me if I'm wrong.
IT Engineering is more inclined towards the software solutions for business problem solving. IT engineering would deal more with programming, databases, applications. In other words, it deals more with the 'Information' part of the 'technology'
.
Computer Science Engineering, on the other hand, deals with the 'computer itself' including study of hardware & operating systems. Computer Science students should know about registers, multitasking kernels, data/address buses etc.
A detailed answer is available here -
WikiAnswers - What is the difference between computer science and information technology