The HTC One M9 wasn't as improved as many hoped, and many fans were very disappointed of the almost identical design of the new model, while on the front side you won't notice any changes, the camera from the back has a square lens, instead of a circular one. The Galaxy S6 Edge has the same specs like the Galaxy S6, but its screen is curved on both sides.
Designs and DisplaysWhile the One M9 has a typical design like most of the HTC devices, featuring a metallic back, curved on the edges, and two horizontal lines at the top and bottom, which hide the radio antennas. HTC has added a dual-tone look, and some phones have the metal frame painted in pink (rose gold), while the back is gold or silver. But there are also variants with a single color, such as gunmetal gray, amber gold or pink. On the front side, you'll see the two BoomSound speakers enhanced with Dolby Audio technology. The device weights 157grams, it measures 144.6×69.7×9.6mm (it's 0.2mm thicker than the M8) and its display has the same size and resolution as the one from the One M8 - 5-inch (Super LCD3) supporting 1080x1920pixels at 441ppi.
The Galaxy S6 Edge has a glass back available in White Pearl, Black Sapphire, Gold Platinum or Green Emerald colors, the frame which covers the edges is following the screen which is curved on the right and left sides and the diagonal of the Super AMOLED measures 5.1-inch, but the resolution is higher at 1440x2560pixels (577ppi). Also, the images look more vibrant, oversaturated, and sharper. The device is a bit shorter, but much slimmer than its rival, measuring 142.1×70.1x7mm, while it weights 132grams.
HardwareThe One M9 is one of the first flagships that came equipped with a Qualcomm MSM8994 Snapdragon 810 octa core processor clocked at 2GHz, but many fans complained about the over heating issues which appear after a few minutes of overuse. But the processor is very fast and it supports multi tasking and complex games, as the configuration is very advanced, being helped by the Adreno 430 graphics and 3GB of RAM. If you need extra storage because 32GB is not enough for you, then you can add a microSD card and expand the capacity up to 200GB.
The Galaxy S6 Edge is as powerful as the Galaxy S6, featuring the same processor, an Exynos 7420 with four cores clocked at 1.5GHz and four cores are running at 2.1GHz. In all tests, the Samsung flagship proved that it is very capable and better than many new devices which are powered by a Snapdragon 810 processor. The Galaxy S6 Edge has a Mali-T760MP8 GPU, which is backed by 3GB of RAM, but the internal memory is unexpandable and available in variants of 32/64/128 GB.
Cameras and BatteriesThe One M9 has an advanced main camera with a higher resolution of 20MP, but the list of features is poorer, as it offers only autofocus, dual-LED (dual tone) flash, HDR and 4K video capture. The Galaxy S6 Edge has a 16Mp main camera with OIS, autofocus, LED flash and 4K video capture, but it has a larger aperture of f1.9, compared to f2.2, which is supported by the One M9, the galaxy S6 Edge has a 5MP front camera which supports auto HDR, while the One M9 takes selfies with a 4MP Ultrapixel secondary camera which supports HDR.
According to GSMArena, the One M9 can offer up to 22 hours of talking time on 3G with its 2840 mAh battery, with four hours more than Galaxy S6 Edge's 2600 mAh battery.
