Fujifilm X-H1 has a 24.0MP APS-C (23.5 x 15.6 mm ) sized CMOS sensor and features X-Processor Pro processor. On the other hand, Fujifilm X-H2S has a 26.0MP APS-C (23.5 x 15.6 mm ) sized Stacked BSI X-Trans sensor and features X-Processor 5 processor.
Another similarity between these two cameras is that both Fujifilm X-H2S and Fujifilm X-H1 sensors lack anti-alias (Low-Pass) filters. 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-H1 and X-H2S sensor size comparison.
Fujifilm X-H1 and Fujifilm X-H2S 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 Fujifilm X-H1 has 8% larger pixel area compared to Fujifilm X-H2S, it has potential to collect more light on pixel level hence have less noise in low light / High ISO images.