For a reaction $\mathrm{pA}+\mathrm{qB}\to$ products, the rate law expression is $\mathrm{r}=\mathrm{k}\left[\mathrm{A}{]}^{\mathrm{l}}\right[\mathrm{B}{]}^{\mathrm{m}}$ then

(p+q) may or may not be equal to (l+m).
p and q are the stoichiometric coefficients in the balanced chemical equation and l and m are the orders of reaction with respect to A and B respectively. p and q can differ from l and m.