The reaction quotient (Q) is a value that can be obtained by plugging in the values of the required concentrations into the equilibrium law. The equilibrium constant is the value when the reaction is at equilibrium.
Links
[1] https://hootsgo.org/?q=node/6469
[2] http://www2.ucdsb.on.ca/tiss/stretton/CHEM2/equil3.htm