A laptop has a 2.5" drive with different IDE connections to a 3.5" drive. You can buy adapters to enable connection to a standard IDE connector.
As for where the drive actual is, I remove these things regularly and the one thing that is consistant is that they are all different. Unless you tell us the model it will be impossible to say.
However if you have no intention of ever putting the machine back together then a simple removal of all the screws and a disassembly of the case will inevitably reveal the HDD. Be very careful not to damage the pins on the drive though,