Pipe system that you cannot see with your naked eyes. This is because the pipe system is underground, underwater, in the wall etc.
Pipe system that you can see with your naked eyes. Like, like, hmmmmm… Well, any pipes system that you can see is linework.
This when the pipe is connected to valve, tap, filter etc.
Well… it is just the hollow cylinder or the tube. That is all. Easy Peasy Lemon Squeezey!
When my senior asked me the meaning of these four words, I could not answer. Then I tried to Google and check Wikipedia. The only correct answer I could find was for pipe. Other three words were and are not available. I had to put are as well because, before I post this, I recheck the terms in Wikipedia…
Still not there.
My senior, after observing that I was totally lost, generously told me the true meaning of those words. Correct only for the oil and gas world usages mind you…