Question

what is the difference between displacement and double displacement (one for each)

Answer 1

in displacement reaction one high reactive element displace less reactive element
and
the reaction in which two different atoms or group of atoms are mutually exchange

Answer 2

the reaction in which one element of surprise displace another element from its composed displacement element from its compound.
Ex. silver nitrate copper copper and nitrate silver.
and
double displacement is a reaction in which two different atoms or group of atoms, ions are displaced by other atoms or group of atoms, ions so double displacement.
Ex. (sodium sulphate ) ( Barium chloride) ( barium sulphate) ( sodium chloride).