What are the major differences between the collector characteristics of a BJT transistor a...

What are the major differences between the collector characteristics of a BJT transistor and the drain characteristics of a JFET transistor? Compare the units of each axis and the controlling variable. How does I_C react to increasing levels of I_B versus changes in I_D to increasingly negative values of V_GS ? How does the spacing between steps of I_B compare to the spacing between steps of V_GS ? Compare  to V_P in defining the nonlinear region at low levels of output voltage.