Canon A2300 has a
16.0MP 1/2.3-inch (6.17 x 4.55 mm ) sized CCD sensor . On the other hand, Canon ELPH 300 HS has a
12.0MP 1/2.3-inch (6.17 x 4.55 mm ) sized BSI-CMOS sensor and features DIGIC 4 with iSAPS technology processor.
Below you can see the A2300 and ELPH 300 HS sensor size comparison.
Canon A2300 and Canon ELPH 300 HS 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 Canon ELPH 300 HS has 32% larger pixel area (2.34µm2 vs 1.76µm2) compared to Canon A2300, it has larger pixel area to collect light hence potential to have less noise in low light / High ISO images.