The main reason why the market-oriented agriculture is more productive than the subsistence agriculture are the methods used during the production.
The subsistence agriculture is focused on a farming that involves the traditional methods, with almost no mechanization involved, the seeds that are used are not of high quality, the protection of the plants is very limited, and very often it is totally dependent on the nature.
The market-oriented agriculture, on the other hand, is heavily mechanized, uses high quality seeds, and all the newer innovations that protect and improve the plants are heavily used. Because of this, this type of agriculture produces much bigger quantity, but also quality.