The Dixiecrats and the AIP were not really the same party, because they were led differently. But they had somewhat the same ideologies, geographies and voters.
The Dixiecrats were led by Strom Thurmond, an aristocrat. He was pro-business and particularly popular among business owners in the coastal regions the south, and won his native South Carolina, plus the Gulf states of Alabama, Mississippi, and Louisiana in the 1948 Presidential election.
The AIP was led by Governor George Wallace of Alabama, who was a champion of the poor white (often union) working man. There are some authorities that believe that Wallace's racism was less a reflection of his personal beliefs than a matter of political expediency. His career took off (among white voters) when he started using anti-black rhetoric. In his 1968 Presidential campaign, Wallace won the three Gulf states, plus Georgia and Arkansas. Interestingly, he did not win South Carolina, which Thurmond held for Nixon.
In a "forced choice," Thurmond much preferred the (post 1964) Republican party to the Democrats, and eventually became a Republican. Wallace ran on a third party ticket saying "There's not a dime's worth of difference" between the two major ones.
So the two parties were not the same, even though they were both based in the deep South and were anti civil rights.