Difference between the two options under model two tab for three stage least squares?

[Mark Baskett]

In stata after going to statistics-->endogenous covariates ---> Three stage least squares and then to the model 2 tab, whats the difference between the two options,


1. Exogenous variables not specified in systems of equations:

2. Full list of exogenous variables:

What does it do differently?

Thanks

Mark