There is a lot of cross-sector mish-mash when it comes to engineering. Extremely broadly speaking-
Chemical = oil industry
Mechanical = anything that moves
Electrical/Electronics = electricity. From power stations to robotics
Civil = bridges (LOL) general construction
They're the 4 main ones. others are just bits and pieces which take things from those disciplines. There are others like systems engineering that are very broad, but they all underly the same principles- and the common language is mathematics. So if you like applying mathematics to solve the worlds problems, then engineering is for you.
The point of University from industries point of view is to learn how to keep learning. I studied Electronics Engineering, I now do high level project management in my job for a massive engineering firm. My job could easily be done by a Mechanical or Chemical Engineer. Indeed, I've often been put on thermodynamics work when the aerospace engineer beside me works on making a prototype circuit board. we're really doing the jobs each other would be more suited for, but that isn't really relevant. Sure, if you want to make chips for intel- then electronics will get you there. If you want to do production lines, then a knowledge of systems and mechanical is probably more relevant.
With the courses, a lot is similar- the maths for instance. You'll all learn how to do partial differential equations, but whilst the mechanical and aero undergrads learn thermodynamics equations, electronics students will do laplace transforms. The projects you do are based on your course too, and to the university you study at. I went to Southampton and did nanotechnology in their new clean-rooms. I also was involved in high voltage testing in my electrical modules, blasting samples with thousands of volts in the name of research. Mechanical eng students I knew did various investigations on regenerative breaking systems, aero guys worked on a new parachute for skydivers, whilst the electronics guys made a submersible robot.
This stuff wont be until your third of fourth year though- which gives you time to try all sorts of different things and discover which modules you like, which you're good at, and which you never want to see again as long as you live.
I applied for several universities all with different courses- Electronic Eng, Systems Eng, Physics, General Eng, Nanotechnology. I ended up picking out of a hat, and I still don't regret it. (Tip: if you feel disappointed picking one course out of a hat, its because you don't really want to do it, deep down. listen to that, and pick again)
If I were you, do systems. Its a relatively new discipline, but key, and there are very few engineers out there that understand it, so it's nice and employable. Failing that, Mechanical would be my next choice- but thats based on that one sentence you wrote about liking factory machines. I wouldn't worry too much about the electronics side of things- every engineer will have to work with computer systems, and you'll learn plenty about that.
You'll have plenty of job opportunities after uni regardless, particularly if you go out, take the initiative and work over a summer or two at a firm.