What is the main way a representative democracy differs from a direct democracy?

The direct democracy is different from the representative democracy.

In direct democracy, the citizen's of a country uses their voting right or power to elect the member while the public directly elects government officials. Representatives are elected from a district or parliamentary constituency or represent all voters in several proportional arrangements.

Mixed system is used in some countries. Although representatives in such a democracy are elected by the people, the representatives themselves decide the policies to act in the public interest.