I'll say that the 'Zero' products have gotten quite good. Not indistinguishable, but closer than I expected. On a couple of occasions I've inadvertently purchased real Dr Pepper instead of Dr Pepper Zero and not realized I was drinking the real thing. That's high praise for the Zero version (notably, the Diet version of Dr Pepper, while it has a following of its own, is extremely unlike real Dr Pepper).

I don't know but I recently drank coca cola which my brother ordered and then after a few days, I decided to drink diet coca cola because I was discussing it with my brother and he mentioned that diet and normal coke are the same price and I started wondering if there are negative effects to normal coke and not much for diet coke and they both are same price and I am drinking it for the taste, then diet coke makes the most sense so I decided to order it

Not sure if its just me though but after drinking both diet coke and normal coke the taste gap between diet coke and normal coke felt really huge to me.

You mention about Dr pepper and how strikingly similar Dr Pepper zero is, what are some other drinks which have a genuinely similar.

But now realizing this, I think that there is a difference between diet, zero and normal variants, this is the first time I am discovering this. Time to drink coke zero and coke but the winters are really cold so I might have to wait this winter season

I can't drink normal coke, it disgusts me, leaves an unpleasant sensation on my teeth, probably the sugar, but love the zero. It's also zero cal, which is a huge bonus.