Overall, as we already said, the Z4 looks a lot like the Xperia Z3, though some subtle changes are clearly visible - including the larger front-facing speakers which have a slightly different position than on the Z3.
It's said that the Z4 measures 146.3 x 71.9 x 7.2 mm, which means it's almost the same size as the Xperia Z3 (146 x 72 x 7.3 mm). Thus, we're expecting the new handset to sport a 5.2-inch display. It's not clear if Sony will use a 1080 x 1920 pixels, or a 1440 x 2560 pixels panel, but it might go with both variants.
The Xperia Z4 will definitely run Android 5.0 Lollipop, while other features are expected to include Qualcomm's octa-core Snapdragon 810 processor, a 20.7 MP rear camera with Sony's new IMX230 sensor, and 3 GB or 4 GB of RAM. We're pretty sure that Sony will include other novelties as well, but for now that's all we know. The Z4 should be officially announced and launched sometime this summer. Interested?
source: Nowhereelse (translated)