Sedition, treason are comparable when they mean an offense against a state to which or a sovereign to whom one owes allegiance.
Sedition applies to conduct that is not manifested in an overt act but that incites commotion and resistance to lawful authority without in itself amounting to insurrection.
Treason applies to conduct that is manifested by an overt act or acts, is variously defined by various governments and at various times but typically has for its aim the violent overthrow of the government, the death of the sovereign, or betrayal to or aid and comfort of the enemy.