can redox reaction be double displacement or displacement reaction???
Redox reactions can be displacement reactions. For example, Zn displaces copper from copper sulphate solution is a redox reaction, in which Zinc is oxidized and copper is reduced.
Zn + CuSO4 → Cu + ZnSO4.
Double displacement reactions are not redox reactions, as they do not involve change in oxidation number of either of the reactant.