Consular processing vs AOS


Would someone explain the difference between consular processing vs Adjustment of status? What is the applicability, pros and cons of each? My H1 extension (after I140 approval) has a RFE and wonder why employer is suggesting consular processing option.

Adjustment of status is when I-485 is being applied. This doesn’t apply to H-1 extension.

Consular processing is when appearing in-person at a consulate for an interview - visa or green card.

What’s the reason for RFE?