For example let's say I want to start at Sol and go to Segovia for a day trip using the fast train service from Chamartin. I know I have to first get to Chamartin. I have seen posts that say 'don't take the metro from Sol, take the Cercanías". I looked up the Cercanías on Renfe and sure enough a lot of trains and very short rides from Sol to Chamartin.
So what will I experience when I get to the Sol metro and I want to take the Cercanías to Chamartin? Different entrance to the station, different platforms? Different ticket windows selling tickets? Thanks in advance.