what do you mean by graph for budget?
ok I get what you mean. Normally, people would use the word as demand instead of budget.
From wiki, in consumer theory, an inferior good is a good that decreases in demand when the consumers income rises, unlike normal goods, for which the opposite is observed.
So, you can only see the difference when you plot it against income. Other than that, it will have to depend on the elasticity of demand.
they look the same because they still follow the basic rules of demand and supply. The only difference is due to income