Hey dear, in engineering there are various branches with several subjects in it. The first year is same for all the branches, students have to learn same subjects. From 2nd year onwards subjects of branches changes like in mechanical your main subjects are SOM, fluid mechanics, heat transfer,thermodynamics, theory of machines, design of machine elements, material engineering,manufacturing technology , etc. In cse the subjects are , dot net, computer networks, data structures, theory of computation,java, python , etc. In ECE you basically learn about the network theorems and transformers, feeders.