There is lot of confusion between Emulation and simulation. In this ppt we tried to give brief description regarding Emulation & Simulation.

1. What Emulation and Simulation Means
by :
Anil Joshi

2. Introduction :
I don't think emulator and simulator can be compared. Both mimic something, but are not
part of the same scope of reasoning, they are not used in the same context.
Emulation : Is derived from the word æmulus, which means "striving, rivaling," and is
related to "imitate" and "image," which suggests a surface-lever resemblance.
Simulation : Is derived from the word similis mean "like", as does the word "similar," which
perhaps suggests a deeper congruence.
Generalized Form:
Emulation : Is "the endeavor to equal or to excel another in qualities or actions"
Simulation : Is "to model, replicate, duplicate the behavior, appearance or properties of".

3. Emulator (For usage as a substitute)
 An emulator will always have to operate close to real-time
 An emulator can replace the original for 'real' use
Lets consider a real example,
Say you want a circuit to work like a ROM circuit, but also wants to adjust the content until
it is what you want. You'll use a ROM emulator, a black box with a physical and electrical
interfaces compatible with the ROM you want to emulate. The emulator will be plugged
into the device in place of the real ROM. The motherboard will not see any difference
when working, but you will be able to change the emulated-ROM content easily. Emulator
will act exactly as the actual thing in its motherboard context but there will be additional
functions visible only to the designer, out of the motherboard context.

4. Simulation (For analysis and study)
A simulator is an environment which models but an emulator is one that replicates
the usage as on the original device or system.
Cannot be substituted with real system
Lets consider an example for simulation:
Plane simulator, a car simulator, etc. When you go for learn driving they provide you
system which looks similar to a car, but its not exactly the same. It only replicates some
of the properties to show user how it may behave in different situations.

5. Conclusion :
As a conclusion, the Emulator is a real thing
intended to work some times more smarter,
the Simulator is a model intended to trick
the user to see how things will look further.