Hi,
The ELM 327 interface is "smart" and decodes the data on bus into numbers / text. This means it only works with standarised protocols, regardless of the software used. The VAG-COM interface is "dumb" and just changes the the voltage levels to suit the computer. This menas the software can work with non-standard protocols like the early airbag system. The VAG-COM does not support CAN so is of limited use on newer vehicles.
Robert G8RPI.
