In technical terms yes both are just PC's or personal computers. But as Yami said, Apple doesnt offer you a choice. You get a list and you select from that list and that is what you get. As for other machines you get to choose everything. From the mobo, to the CPU to which RAM you use all the way down to which mouse and keyboard you want to use. You are not forced to just select an item from a list and get only that option. Unless you buy from Dell, HP or one of the other prebuilt companies that is.
But for the most part the problem was very distant so long ago. This was due to the fact that when Apple's were on PowerPC chips they were only able to be used on those machines and had very little interaction with the majority of "PC" users out there. It was for this reason that Windows was the target for virus and spyware people. As they could get the most bang for their buck with their infection. But once Apple switched to Intel based processors the problem has gotten less distant between the 2 companies.
Apple's big claim to fame was "It just works" and they misnomer that they dont get infections. Well you wave a steak in front of a dogs face for long enough, sooner or later it will bite you. Since Apple kept on claiming they were hack proof and infection free they became a target much like Windows did. Now you got all the virus writers attacking OS X like it was their new toy on XMas as a kid. They want to show that all the claims aint true and they have succeeded.
The proof is out there as well. Just look up Black Hat and see the results in recent years. Apple has been the first OS hacked and it happens within minutes of the competition starting.
Now add into that the price of the units. When you can get a Dell based PC for about half the cost of an Apple of equal specs the question has to come in as to why. Why is it that you are spending so much more on an Apple based PC? There is yet to be any reason behind that other than Apple is demanding that price. People pay it so there is no reason for Apple to reduce prices. They have the demand for the units at that cost so they supply them. Only when the time comes when the consumer starts to demand an Apple PC at less cost will they be supplied at that cost.
The only advantage to any system is if it does what you want the way you want it. That is all there is to it. If you can do what you want and you have the means and desire to purchase an Apple based PC, then that is what your going to do.