Fujifilm X-T1 IR has a
16.0MP APS-C (23.6 x 15.6 mm ) sized CMOS X-TRANS II sensor and features EXR Processor II processor. On the other hand, Olympus SP-590 UZ has a
12.0MP 1/2.3-inch (6.08 x 4.56 mm ) sized CCD sensor .
Another difference between these two cameras is that Fujifilm X-T1 IR's sensor lacks anti-alias (Low-Pass) filter. Removing anti-alias filter increases the sharpness and level of detail but at the same time, it increases the chance of moiré occurring in certain scenes.
Below you can see the X-T1 IR and SP-590 UZ sensor size comparison.
As seen above, Fujifilm X-T1 IR has a 13.3x Larger sensor area than Olympus SP-590 UZ. 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.