Is there a difference in gnocchi between baking, steaming, or boiling potatoes?
There are several styles of gnocchi.  For potato gnocchi, use starchy, russet potatoes.  Boiling, steaming, or baking will all work.  I prefer baking, as it is easier to control the moisture content when mixing with eggs and flour.  Pass your cooked potato through a ricer or food mill before adding eggs and flour (though some folks use a fork and like rustic, small chunks of potato.) Try to avoid over-mixing for the lightest gnocchi.  Avoid waxy varieties.