TM original face mask sizes varied between castings/moldmakers, the orignals were slightly warped.
The SL face is much the same as the EFX, fractionally bigger.
The dome is more rounded on the EFX and the SL is tighter in the dome cap. the flaring on the flanges differ.
Much more detail on the SL where as the EFX is toy like and it has been cleaned and features a more inaccurate but sharper Y crease in the peak.
Very doubtful owners could make direct photo comparisons that show this as you normally have both TM and SL agreements
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All 3 could make an impressive Vader but you would need much bigger mods to an EFX and I would imagine much skill to pass it off as a finished and accurate Vader. Even then.
Bare in mind the SL face also has it's flaws. I'm not going to state what they are. As does the TM. Measurements are fractionally larger on an SL face. We are talking small measurements that are barely noticed.