Rita is predecessor to Dharma and is the Original Rig Vedic concept which refers to the principle of natural order which regulates and coordinates the operation of the universe and everything within it. Rita refer to the moral rules that are levied on us by society. It’s our prerogative whether we follow them or not.
Dharma refer to our duties that we have to perform. Dharma is so called, because it holds the people. Etymologically, Dharma is derived from the root Dhr—to hold—and its meaning is ‘that that which holds’ this world