Sony has announced three new flagship handsets in the Z5 family. There's the regular Z5, but it has been joined by the predicable Z5 Compact, and the less-than-expected Xperia Z5 Premium, which brings a shine to things, literally. 

It's a threesome of handsets, closely matched on the spec sheet, but not entirely the same. So read on and we'll guide you through the headline differences in Sony's latest flagship handsets. 

All the new handsets exhibit Sony's OmniBalance design, so there's a high degree of similarity between these handsets, with a metal frame and glass front and back. All are waterproof, with IP65/68 rating. 

The Xperia Z5 and Xperia Z5 Premium are the same, apart from the size, but they are slightly different in design around the edges compared to the Z5 Compact. The smaller handset has a seamless finish, whereas the two larger handsets have reinforced corners.

The Sony Xperia Z5 Premium measures 154.4 x 75.8 x 7.8mm, the Xperia Z5 measures 146 x 72 x 7.3mm and the Xperia Z5 Compact measures 127 x 65 x 8.9mm. As you'd expect, the Compact is the smallest, but it's also the fattest. The weights stack up as: Premium, 180g; Z5, 154g; Compact, 138g.

All the Z5 family have the same finishing treatment, getting a deep frosting, providing a lovely feel in the hand. The Premium, however, has a special finish in the chrome version, which has a mirrored back. 

The Sony Xperia Z5 Premium is the world's first 4K smartphone. It has a 5.5-inch display with a 3840 x 2160 pixel resolution, for a staggering 801ppi. 

The Xperia Z5 has a 5.2-inch 1920 x 1080 pixel resolution display, with a 428ppi. The Z5 Compact has a 4.6-inch 1280 x 720 pixel resolution, for a 323ppi.

All the displays use the same LCD IPS display technology, all are punchy with colours and come with Sony's X-Reality boosting that we've seen on devices before. On the Z5 Premium, X-Reality also handles 4K upscaling.

The display on the Premium is excellent, it's very sharp, probably sharper than you can see and the highest resolution of any device you'll find around. The Z5, perhaps, could be sharper, as many devices of this size (SGS6, LG G4) are higher resolution, but it still looks great, which is the important thing. 

While the Z5 Compact display is still nice and punchy and bright, the lower ppi makes a difference: it can't produce the detail that the bigger displays can and it's noticeably less sharp.

All the new Xperia Z5 handsets are equipped with the Qualcomm Snapdragon 810, but they differ in RAM. The Z5 Premium and the regular Z5 both have 3GB, so are likely to be a touch faster than the Z5 Compact that settles with 2GB of RAM. 

The Z5 Compact will offer 16GB of storage, while the Z5 and Z5 Premium will have 32GB. All have microSD card slots, so you can expand storage.

The size of the battery is different across the models too. The regular Xperia Z5 has a 2900mAh battery, the Xperia Z5 Compact settles at 2700mAh and the Z5 Premium is 3430mAh. All promise two days of battery life. 

Sony has had some great performing phones in the past when it comes to battery life, but we're yet to see the affect that the 4K display has on battery life. Sony has integrated memory in the display, meaning it can cut power to the CPU once the image is shown, in an effort to further reduce battery drain. 

All the Z5 family have the same camera, all capture 4K and all offer the same features, with the same lens, fast autofocusing and image stabilisation.

The new camera has a 23-megapixel sensor, offering a Hybrid AF system that's said to be the fastest of any smartphone, supported by a newly enhanced optical image stabilisation system.

All have the same 5-megapixel front camera also.

The range of functions and features offered across these devices is the same. Unlike some other manufacturers, Sony is matching these devices to a very high degree. All have the same user interface and the same capabilities, like PS4 Remote Play and support for high-res audio. 

The Premium, naturally, has a display the others can't match. Both the Z5 and the Z5 Compact might be called out for not being progressive enough in the display, but no one can say that about the Premium. The reduction in RAM on the Z5 Compact probably won't make a huge difference to the experience, if the performance of its predecessor, the Z3 Compact is anything to go by.

The only thing we don't currently know is the price. We suspect that the Sony Xperia Z5 Premium will have a premium price, cascading down for the other devices. We suspect the Z5 will be around £550 and the Compact around £450.