If you want to run Windows on a MacBook through BootCamp you need to separate the systems in different partitions, that means you will have exactly a machine with Windows and OS X operating systems, but you can't access both at the same time. To accomplish simultaneous tasks in both operating systems you will need an emulator or a virtual machine. An emulator is a program that simulates the working of a system. The most known are the emulators of video game consoles, with it you can run on your computer those games that have not been released for that platform.
The emulator will simulate the system of a specific machine, therefore, the processes will be identical. If you use a Super Nintendo emulator it will perform all the actions that the video game performs. You can even use an adapted control for USB port and it will work as if it was plugged at the physical console. The emulator makes the program believe it is running on a real machine. The big disadvantage of emulators is the loss of performance. The big disadvantage of emulators is the performance loss. To emulate an old system with fewer requirements you need a machine with more performance capacity than the original machine.
Virtual machines run programs like a real computer. IBM defines a virtual machine as a isolated copy of a physical system. After installing the program for creating the virtual machine, you can create a virtual hard disk, and then you can run an entire operating system. On the virtual machine you can install other software such as the physical machine. For example, you can have a virtual machine running Windows and install specific software for this system. Many developers use virtual machines to test new programs and their performance in different systems without having to run them on several different real machines.
Virtual machines offer greater performance than the emulators because they are not pretending to be a system, they are running the true system on a virtualized machine.
Image source: Forbes
This performance difference between the two types of software makes it easy to choose one of them. According to your needs, if you want to use Windows to run programs incorporated into the operating system, or to simulate video games game without a computer version, an emulator should be enough for you. To use Windows more fully, with more features, and be able to install other programs, such as games with only the Windows version, you will need to adhere to a virtual machine.
Do you already know which option fills your needs? Do you already make use of some emulator or virtual machine?
Tell us in the comments!