Sapere and conoscere both are defined in English as to know. However there is a slight difference.
Conoscere = to know a person, place or thing
i.e. Io conosco Gianni/ I know John.
Sapere = to know a fact or have a talent for something.
Io so che Roma e' la capitale d'Italia./ I know that Rome is the capital of Italy
Io so suonare la batteria. / I know how to play the drums.
Passato prossimo is also different.
Conoscuito = met
Ho conoscuito Gianni sabato/ I met John on Saturday
Saputo = found out/revealed
Ho saputo che Gianni e' il fratello di Mario/ I found out that John is the brother of Mario.