Sony T90 has a
12.0MP 1/2.3-inch (6.17 x 4.55 mm ) sized CCD sensor . On the other hand, Sony TX10 has a
16.0MP 1/2.3-inch (6.17 x 4.55 mm ) sized BSI-CMOS sensor and features BIONZ processor.
Below you can see the T90 and TX10 sensor size comparison.
Sony T90 and Sony TX10 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 T90 has 32% larger pixel area compared to Sony TX10, it has potential to collect more light on pixel level hence have less noise in low light / High ISO images.