Hello alexhero and klikya,
Below you will find a link regarding AOS vs CP. Most people who are already in the states opt to do AOS once they call USCIS and determine that they are eligible for AOS. CP (Consular Processing) would require you to go back to your country of origin to a US consulate in your country to apply and interview for your green card.
You indicate CP or AOS on the DSP-122 form question 4. By indicating "BCIS" you are letting KCC know that you would be doing AOS. AOS gives you the flexibility of adjusting your status to permanent resident without having to go home to your country of origin if you are already in the states. Otherwise name the US Consular office in your country of origin where you would like to process your application. The latter indicates to KCC you would prefer to do CP.
CP vs AOS link