Lead loops in east coast hip hop?

I listen to these tracks from the late 90's, and I hear those chill
lead loops. Most of them sound a bit acoustic more like guitar and
piano, but i just cant find them.
sample songs:-

Nas - Purple
50 Cent - Window Shopper*****
Jay-Z - Hard Knock Life (Ghetto Anthem)**

ANY information will help I produce instrumentals and I really need
that.