I have had this argument on the thread I linked, read it please.
I am not confusing them, I am comparing them. There was a canal from the Red Sea to the Nile built/rebuilt by the Egyptians, Greeks, Romans and Arab Caliphate, it served exactly the same purpose as the Suez canal and was the same size as the Suez canal was when it was originally built. In fact, a canal from the Nile to the Red Sea is actually harder to build because it is fresh water to sea and therefore requires locks, whilst the Suez is free flowing seawater and therefore just a hole in the ground.
The reason Napoleon didn't build a Med-Red sea canal was the same reason as all those before him, his engineers did not accurately measure the sea level difference. Napoleon thought it was impossible because his engineers told him the sea level difference was 10 metres, rather than an almost negligible difference as it actually is, requiring building locks (which are expensive). Had he been given accurate measurement, he would have built it.
There's ten pages of stuff in your link. Finding a specific argument from that amount of text is like finding a needle from a haystack. And that Napoleon example just shows that engineers of the Napoleonic era weren't competent enough to build it. The fact that none of the projects really offered anything more than a temporary solution at the best, is a strong evidence supporting the claim that the task wasn't possible before the industrial era. They would have done it before if it was possible and realistic.