B.Tech Electrical and Instrumentation Engineering

Hi,
Let me breakup the syllabus/ contents of these interrelated and confusing options.
Electrical engineering is all about learning to handle electrical machines like motors-DC, synchronous AC, asynchronous AC, etc., layout and design of the different types of electrical equipment and power systems used in the industry, control systems (even in electronics) used for automation and how they're used for designing advanced electrical and electronic systems, and if your college offers, a course on communication systems which would lay base to the vast telecommunications and network engineering topics.
Instrumentation engineering is a specialisation of electronics engineering and involves a deeper understanding of instruments used in various industries, using electronic sensors and transducers to actually implement the control systems which electronics engineering teaches you.
Electronics engineering is a vast area, consisting of VLSI (Very large scale integrated) design, robotics (which requires some basic knowledge of electronics, mechanical and software, and is better to focus on one area of robotics rather than all the three), communications and the evergreen embedded systems design which leads you to advanced VLSI, computer architecture (more computer science oriented) and advanced networking systems courses (if you also want to add communications, it goes great with networking).
Robotics involves, as I said, basic knowledge of electronics, mechanical and software, as robots are basically mechanical devices, built with electronic components, driven by software. Mechatronics basically combines electronics and mechanical aspects of robotics.
I hope this helps you to choose wisely.
All the best.