I heard that, although we can do chazarah and kedusha when we have up to 4 men who have prayed in a 10-man minyan. there is a difference of this for a minyan of 10 people who have not yet prayed, what would it be and what is the source?
If I understand you correctly, you mean to say that if there are 6 out of the 10 people in the minyan have not yet prayed that it is permitted to say chazaras hashatz and kedusha, even though the other four already prayed. The source for this is the Mishna Berura 69-8.
It is however preferred that there be ten men that have not yet prayed. This is because there are numerous poskim (see sources) who say that in order to consider the prayer tefilla b’tzibbur we need 10 men who have not yet prayed. Although the other four allow us them to say kaddish and kedusha, however the prayer is still not considered tefilas b’tzibbur. Therefore, it is preferred to have ten people that are actually praying together.
Yad Eliyahu siman 7, Teshuvos V’hanhagos 3-33 in the nשme of the Brisker Rov, Orcos Rabeinu 1 (old edition) pg. 51, Igros Moshe O:CH 1 28-30, Sharei Halacha 69-1, Eishei Yisroel 12-7 ftnt.15.