Which aqueous solution has higher concentration`:1` molar or 1 molal solution of the same solute ?

Explanation

In aqueous solution, 1M solution means 1 mole of the solute in 1000 cc of the solution whereas 1 m solution means 1 mle of the solute in 1000 g of water ( = 1000 cc of water). Total volume of 1 m solution gt 1000 cc due to presence of extra 1 mole of the solute. Hence, numer of moles/cc in 1 m solution will be less than that in 1 M solution. In other words, 1 M is more concentrated than 1 m.
In non-aqueous solution, 1 M can be greater than, less than or equal to 1 m, depending upon the density of the solution.