The 737-700 has a max take-off weight of 154.500 lbs, the BBJ
's max take-off weight is 171.000 lbs.
is a hybrid 737 modified for long range corporate service. It has the shorter -700 fuselage mounted on the higher gross weight -800 wings and landing gear.
This allows the BBJ
to carry extra fuel in the lower cargo compartments which gives it longer range than the -700.
Technically the BBJ
is known as a B-737 IGW (increased gross weight)