What is the difference between Megaloblastic and Non megaloblastic anaemia, both being Macrocytic?

What is the difference between Megaloblastic and Non megaloblastic anaemia, both being Macrocytic?

Hypersegmented Neutrophils (> 5 lobes) - megaloblastic anemia

No hypersegmented neutrophils - nonmegaloblastic anemia

Peripheral blood smear is the initial investigation for macrocytic anemia to look for megaloblastic changes ( hypersegmented neutrophils)