Hi Harsh,
The "tech world" is gigantic, constantly growing & forever changing. New types, job titles & capabilities are constantly being added by innovative & curious thinkers. I hope to answer your questions & help you in your journey... so let's break it down like this:

{Insert any Type} of Engineering: This is going to be what's considered as a very technical role. Engineers in any field are usually the brains, the nuts & bolts, the creators & guru's or experts of a certain field. For example, a storage engineer would be an expert on all things storage; they really grasp the principles & even contribute to improving or creating new storage technologies.

Now specifically - your mentioned areas...

Electronics: you'll be the guy who knows everything there is about the behaviors of electrons, and how to design, test and develop things that use electricity. Think robotics, mobile device, medical & nano-tech hardware.

Communications: the world loves being connected; the faster; stronger, broader that connection, the happier. And connectivity is increasing with wearables, the internet of things & phones! You'll be the guy designing and fortifying the systems that make those connections possible. This blends into a lot of tech areas...

Computer: {the name really needs to change, it's a bit out-dated in my opinion} So this is a very broad area, it can include software development, data networks, hardware, systems, databases, architecture, the list is endless. You'll be the guy who probably knows a lot about everything tech. Perhaps find a few of those things to focus on.

Pro's & Con's:

Con's: you have to figure out what in this area interests you. With so many possible's all I can say is: good luck :)

Pro's: - you will ALWAYS have a job. Always. You might lose it occasionally as companies downsize or poorly handle their budget, but you'll have 5 more before the day is over.. - constantly changing - can make positive, powerful changes for the better in peoples lives - unlimited choices - you can work in any industry in any part of the world because at the end of the day, it's all 1's and 0's right?

The key is to figure out what you like - that when you wake up, you're excited.