Computer science is the broad group among these 3. Most people who practice computer engineering do also, to some degree, practice computer science, and all people who study MCA which is much more focused on computer applications, are computer scientists. Computer engineering focuses far more on the hardware design of a computer. On a hardware level computer engineers solder circuit boards, know much more about electronic circuits, and program in much lower level programming languages such as assembly, C, and C++. MCA programmers are almost completely opposite. They focus completely on the software application side of programming, more user interface, programming in Java, Python, rarely C++.
