Is this equation right HCl + NaOH ---> H2O + NaCl or NaOH+HCl--> NaCl + H2O & what the difference ?

Either of the equations in your question is acceptable, although traditionally the acid comes first in the reactants and the salt comes first in the products. ##"HCl(aq)+NaOH(aq)"####rarr####"NaCl(aq)+H"_2"O(l)"##

This is a type of double replacement (displacement) reaction called a reaction. The positive ions ##"H"^+## and ##"Na"^+## have switched places with the negative ions ##"Cl"^-## and ##"OH"^-##. The result is the formation of water and a salt.