Extra-economic constraints are a form of coercion based on relations of direct rule and submission of the working masses to the exploiters; such constraints are characteristic of slaveholding and feudal society.
Capitalism as a system of wage slavery is based on economic constraint. It presupposes the worker's personal liberty but at the same time deprives him in one way or another of the means of production. Therefore, in order not to die of hunger, the working people are forced to sell the capitalist their labour power and experience the oppression of exploitation.