AGR vs. ALH: What's the Difference?

Hello professionals!

Can someone explain the differences between an AGR and an ALH engine?
According to the knowledge database, the only discernible difference between the MKBs concerns the emission standard.
Could it be that the injectors are different? Or was it perhaps only the mapping for the EGR system (not to be confused with the EGR system linked to the engine control unit) that was modified in such a way as to reduce NOx emissions?
Do the mechanical designs of the engines (turbochargers, ESP, DHK, etc.) differ?
Are the control units and sensors identical?

Who knows more?

Sure, here's the translation:

"Thank you in advance."

Regards,
Alex.