They are very similar, but the M5 has mesh covering the entire airdam, wheras the Mtech leaves a gap on both sides. M5 also doesn't come with fog lights, though I think they can be retrofitted somehow.
Anothher small detail is that the pointy tips or jags below the center airdam point invards on the M5 and are angled outwards on the Mtech.
Normally only the M5 sedan comes with the M5 bumper, all other 5s come with the Mtech. Speaking of BMW production line.
That's one reason i went with Mtech, didn't want to turn my car into a poseur M5. No debadging either.
Audio: Jehnert Flatline speakers, Mobridge M1000 DA2 prepro, Helix P-DSP, Zapco Z-150.6 amp, iDock on dash
Performance: Protuned Cobb, AR Downpipes, ER FMIC/CP, DCI, RB turbos, KW V2 coilovers, AEM 320E LPFP/ported fuel rail