The answer to this question would depend on the date one was looking at the southern colonies. Indeed, Georgia did not even become a colony until 1732. By the time of the Revolution, however, the southern colonies shared several basic characteristics, three of which are listed below. The first was that all of them featured significant numbers of black slaves. Regions of Tidewater Virginia and Lowcountry South Carolina had local populations that numbered well over seventy-five percent slave, and both colonies were nearly half black overall. North Carolina and Georgia's slave populations were smaller, but were growing rapidly in the second half of the eighteenth century.
Partly due to economies of scale created by slavery, Southern colonies featured planter elites that dominated the colonies' legislatures. Virginia and South Carolina, because they had the most-developed plantation economies, had the most cohesive and powerful elites, who profited from tobacco in the Chesapeake and rice in South Carolina. In these colonies, these elites often struggled with royal governors for control of government.
Finally, another significant similarity was that each of the southern colonies experienced significant waves of settlement in their backcountry regions. In the second half of the eighteenth century, thousands of settlers, mostly Scots-Irish and German, poured into the Southern backcountry, altering the political, religious, and social dynamics of the colonies.