Artificial Intelligence vs Virtual Intelligence

A virtual intelligence (or VI) is a rudimentary version of an artificial intelligence (or AI), but is incapable of self actualization or sentience. A VI is designed to be an intelligent user interface that can be posed questions about whatever the VI is installed into, and will answer them and be able to give recommendations or instructions. They are designed to simulate natural communication and are often presented as a hologram of a sapient humanoid, generally of the species most likely to access the VI. VI 'Agents' are also available; these are more compact and menial versions of VIs and are specialized for install into very specific parameters, such as ship and vehicle interfaces (think Computer from Star Trek).

AIs are far more advanced than VIs; they are self-aware and capable of learning and independent thought and decision making. The citadel has outlawed any and all research pertaining to AIs as over three centuries ago, the quarians created a race of networked AIs known as the geth, who turned on their masters and ejected them from their home world. Barring the geth, active AIs are incredibly rare, were even so when they were legal, as VIs are generally more than sufficient to get the job done.