Not all features found in real XMM-Newton EPIC images are reproduced in the simulated images. The following table summarises these differences:
| Feature: | Simulated: |
| Poisson noise | yes |
| Off-axis PSF | yes |
| Chip gaps | yes |
| Vignetting | yes |
| Dead pixels (as expressed in the exposure maps) | yes |
| Background statistics | yes |
| Attitude wander (as expressed in the exposure maps) | yes |
| Bright pixels | no |
| Out-of-time events | no |
| Scatter from RGA | no |
| PN low-energy instrumental features | no |
| Pile up | no |
| Random source spectra | no |
| Extended sources | no |