What's the difference between aqueous NaOH and dilute NaOH?
Dilute simply means that the concentration of the solute of interest, in this case $\ce{NaOH}$, is low relative to some reference.  One could imagine a non-aqueous, dilute solution of $\ce{NaOH}$ in, say, methanol.

An aqueous solution is one where the solvent is water, regardless of the concentration of the dissolved solute(s).

So, for example, the following combinations of the terms are possible:


Concentrated aqueous solution - High $\ce{NaOH}$ concentration in a water solvent
Dilute aqueous solution - Low $\ce{NaOH}$ concentration in a water solvent
Concentrated methanolic solution - High $\ce{NaOH}$ concentration in a methanol solvent
Dilute methanolic solution - Low $\ce{NaOH}$ concentration in a methanol solvent