Whats the difference between a Buddha and an arahant?
The attainment of arahantship and Buddha-hood are identical: the attainment of the Deathless (Nibbana) and the complete and irreversible eradication of the defilements, the underlying cause of suffering. It is the Buddha who (re-)discovers the Dhamma on his own; it is the arahant who puts his teachings into practice and follows in his footsteps.