True the "cabin arrangement" is the same on the B752 as on the B738, but the number of seats are 186 on the B738 and 229 on the B752. Overall a difference of 43 passengers of carrying capacity, which means that a B752 can transport more than 23% more passengers than a B738.
Minor correction, the 738 carries 189 pax, and some of the 752's carry 232 pax, most carry 229.