The HTC One M9 made an appearance at the Mobile World Congress and is now available for purchase. The comparable Sony Xperia Z4 will now be delayed until September. Both Android smartphones have very similar features and specs.

Let's compare the HTC One M9 and the Sony Xperia Z4.

The HTC One M9 kept its 5-inch full HD screen with a resolution of 1920 x 1080 pixels. The Sony Xperia Z4 will be slightly larger, with a 5.2-inch screen that displays the same 1920 x 1080 resolution. The M9 has slightly more pixels per inch at 441 ppi, while the Z4 displays 432 ppi. The M9 also offers Corning Gorilla Glass 4 to protect the screen, while the Z4 does not offer any screen protection options.

Both smartphones utilize the Qualcomm Snapdragon 810 processor. The Z4 has more RAM than the M9, with the Z4 offering 4 GB of RAM and the M9 only offering 3 GB of RAM.

Buyers will be able to choose from a 32 GB or 64 GB Z4 when it goes on sale. The M9 sells a 32 GB model. Both devices have a microSD slot that will allow internal storage to be expanded to 128 GB.

Both smartphones offer excellent cameras. The Z4 camera is a 20.7 megapixel camera with an LED flash. The M9's camera is also a 20.7 MP camera, but it comes with a dual-LED flash. Both smartphones have face detection, but the M9 offers smile detection. The front-facing camera of the Z4 will be of better quality than the M9, with the Z4 offering a 5 MP front-facing camera and the M9 offers a 4 MP front-facing camera.

The battery specs on the Z4 have not been released yet, but like the M9's battery it will be non-removable. The Z4 will use a lithium-ion battery (Li-Ion). The M9 uses a lithium-polymer battery (Li-Po). The M9's battery life allows up to almost 22 hours of 3G talk time.

The Z4's extra RAM will make it capable of multitasking better than the M9. Besides that, both smartphones look like they are almost equal. The extra 0.2 inches on the Z4 still cannot equal the pixels per inch that the M9 offers. While the M9 is out now, the Z4 might be worth waiting until September for.