Internal or external hard drives can they all be used both Mac and PC

[alohascott]

I see many drives for sale for Mac's
I also often have mac owners ask me about using one of my PC drives in a mac.

Is there any reason you can't take a regular pc drive and use it in a mac?
is there a different interface or some other reason why mac drives seem higher in price.

 

[alohascott]

Thanks for the detailed explanation.
Tell me about the thinking different part.
I just got an iPhone.