Defensive alignment hasn’t changed all that much in the modern football era. A defense used to be defined by the organization of its front, the number of defensive lineman and linebackers; 5-2, 4-3, 3-4, 33 stack, 4-2-5.
As offenses spread out, defenses utilized hybrid athletes with the goal to be more multiple. Ask a defensive coach now and they’ll say “everyone is a 3-4 or 4-3 or 4-2-5”. The old nomenclature doesn’t tell you very much when nearly every team is a mix of both odd and even fronts, sometimes with the same personnel, and play most of their snaps against spread offenses in Base Nickel.