There are a few differences between the syllabus of these two programmes.
Like in Diploma in Computer engineering and Information Technology, you'll have basic electrical, electronics and applied mathematics and english communication and management.

Other topics included in Diploma in Computer engineering throughout the course are- Programming with C, Introduction to computer concepts, Computer organization, data structures, database management system, computer networks, object oriented programming languages, PC Hardware and Networking, GUI, Web designing, Operating system, Linux, software engineering, software testing, web programming, network security, mobile computing, CASP, Network Security and Management etc.

Other topics included in Diploma in Information Technology throughout the course are- Multimedia and application, system analysis and design, RDBMS, Programming with C, Computer fundamentals, Communication using PC, Design and Analysis of Algorithms, Data Structures, Software Engineering, Website designing, Object Oriented programming, ERP, Operating systems, Computer Organization and Architecture, Computer networks etc.