What was the main feature of the Lithuanian-Russian state?

Most of the Russian lands voluntarily became part of the Lithuanian state, since it protected them from the attack of the Mongols. The Lithuanian state in the military sense was very well developed, but significantly lagged culturally behind the Russian lands. Therefore, most of the government posts in the Russian-Lithuanian state were eventually occupied by Russians. The state did not oppress Orthodox Christians, who constituted the overwhelming majority of the people of the Russian lands. Moreover, a significant part of Lithuanians converted to Orthodoxy and adopted Russian customs.