Sony TX10 has a
16.0MP 1/2.3-inch (6.17 x 4.55 mm ) sized BSI-CMOS sensor and features BIONZ processor. On the other hand, Sony TX9 has a
12.0MP 1/2.3-inch (6.17 x 4.55 mm ) sized BSI-CMOS sensor and features Bionz processor.
Below you can see the TX10 and TX9 sensor size comparison.
Sony TX10 and Sony TX9 have the same sensor sizes so they will provide same level of control over the depth of field when used with same focal length and aperture. On the other hand, since Sony TX9 has 32% larger pixel area (2.34µm2 vs 1.76µm2) compared to Sony TX10, it has larger pixel area to collect light hence potential to have less noise in low light / High ISO images.