Dear Elliott,
A genuflection, made by bending only the right knee to the ground, signifies adoration and it, therefore reserved for the Blessed Sacrament, whether exposed or reserved in the tabernacle…” This is from the Ceremonial of Bishops, #69. So if the pew is in front of the tabernacle, then you genuflect upon entering and leaving. But if only the altar is in front of you, then you bow. The altar is the place of sacrifice and is the center of the Church. One ought to reverently acknowledge this by a bow whenever passing in front of it.
Fr. Vincent Serpa, O.P.