Those games have not been made by Sid Meier. Those are the differences with Civilization I&II
1) The tech tree, units, wonders, buildings, goverments and ages go from ancient ages to future ages, while Civilization stop at modern day science. You can also place cities in the sea or (only in the first one) the space.
1 bis) There are much more units, wonders, buildings, goverments and civilizations than the first 2 Civilization, and the ones that remain not always have the same effect.
2) Instead of producing a caravan and sending it to other cities to gain money, you can just go to a trade advisor and put for sale the goods that your cities produce
3) Instead of using a unit (settler, worker or terraformer) to work the land and produce mines or farms, a bit of the production output of your cities produce "public works" (work more or less like gold) wich is used to place those improvements. You just select them from a menu and, providing you have enough "public works", you place it where you want.
4) Some units have stealth habilities, it mean they can't be seen by regular units unless they want to get to the same square. Those units don't attack like the others, they don't just try to go to the city and the stronger unit wins, but can make other actions: stop city production, kidnap citizens, extract gold from the city every turn, incite a revolt, etc. Also, those games were released before the pacifist mania of the United States and include the option to make terrorist attacks.