At a glance, Black. In four moves black can develope the kings knight, the queens bishop, and castle. White will take five moves to castle. So black is up a tempo. Black appears to have more potential for developement and gain of material.
Who is better in this position?

May I guess these are the moves?
Both 4...Qg5 and 5.Nf3 are secondrate ones. In the final position, Black is more than OK after 6...Nd4, since he has easier development and h2 is weak.
Yes, they are. I have curiosity, why are those moves second-rate? I had in mind, in the final position, after 6....Nd4 7.Nxd4(or 7.Be2 d6 8.c3?? Nxe2 Bg5) 7...Bxd4 8.Qe2 a6 9.Ba4 b5 10.Bb3 Bb7,etc., not letting him to play d4.
Black to play. Who is better and why?