The obvious answer is that an Intel chip is made by a company called Intel and the AMD chip is made by a company called AMD.
AMD CPUs are fine and I have built a couple of PCs that have AMD CPUs and they run Windows well and I have never had a problem with them.
The AMD X2 and the Intel Core 2 Duo are both dual processor CPUs so from that point of view are similar (they do have design differences but that needed bother you)
Generally the "best" CPUs around at the moment are Core 2 Duo's, but having said that a "fast" AMD chip will be better than a "slow" Intel Core 2 Duo chip.
You can compare the speed of the CPUs here (although CPU speed is only one measure of a laptops performance)
http://www.cpubenchmark.net/