Fuji claims that it is exactly the same EVF (Sony-made OLED), but to my recollection the refresh rate of the X-T3 is a bit higher. The main difference (re. the EVF) is the processor of both cameras. The X-T3 has a later generation processor that allows for higher refresh rates. Make sure both cameras are in 'boost' mode when you compare them. Also other features (like brightness and color setting) can cause difference in EVF experience as well as minor changes in the optics in front of the EVF. Fuji isn't specific about changes re. this.
I can't compare anymore since I sold both cameras and switched. From that experience I can tell that the same EVFs on paper can make a great difference in practice. So, always check the EVF yourself before you buy a camera. Esp. when you wear glasses or need to change the diopter.