Question

what is difference between displacement and double displacement reaction?

Answer 1

Displacement reaction is a process were a single element replaces another compound to form as new compound.
AB + X-----> AX + B
Example: Fe + CuSo4 ----> Cu + FeSo4

In double displacement two molecules in different compounds replaces to form two different compounds.
AB + XY -----> AY + BX
Example: AgNO3 + NaCl -----> AgCl + NaNO3

Answer 2

double displacement reactions may be defined as the chemical reactions in which one component of each reacting molecules is exchanged to form products. During this reaction the cations and anions of two different compound switch place forming two entirely different compounds.

* displacement reactions may be defined as the chemical reactions in which the ion moves from one compound to other.