Both Olympus Tough-3000 and Olympus TG-5 have 12.0 MP resolution sensors but Olympus Tough-3000's sensor is 1/2.3-inch (6.08 x 4.56 mm ) and Olympus TG-5's sensor is (1/2. ).
Since Olympus Tough-3000's has a larger sensor area with the same resolution, this means that it also has a larger pixel area hence better light collecting capacity for a given aperture compared to Olympus TG-5.
Below you can see the Tough-3000 and TG-5 sensor size comparison.
As seen above, Olympus Tough-3000 has a 0.0x Larger sensor area than Olympus TG-5. Larger sensors give photographer more control on the depth of field and blurry background compared to smaller sensor when shot in same focal length and aperture.