emulation and simulation

An FPGA on its own is neither a simulator or an Emulator. It is only these things if you want it to be. Quartus has nothing to do with it, other than for compiling and debugging purposes.

If you wanted to simulate a processor, then you could use an FPGA. If you wanted to emulate a processor, then you could use an FPGA. if you wanted to create a new specificially designed co-processor, like an FFT, that talks to a processor, then it is not a simulator, and it is not an emulator. It is a peice of hardware like anything else.