Apple's new iPhones - the iPhone 7 and iPhone 7 Plus - are now available to buy following their announcement on 7 September. Once again, Apple is offering a big iPhone and a smaller iPhone.

We've compared the standard iPhone 7 to the iPhone 6S and iPhone 6 in a separate feature, but this feature focuses on comparing and contrasting the iPhone 7 Plus with the iPhone 6S Plus and the iPhone 6 Plus.

Read on to find out the differences and similarities between the larger iPhones, old and new.

The Apple iPhone 6S Plus measures 158.1 x 77.9 x 7.3mm and weighs 192g, while the iPhone 6 Plus measures 158.1 x 77.8 x 7.1mm and is 20g lighter at 172g. Both offer a metal build that's identical in appearance, though the iPhone 6S Plus is made from a different grade of aluminium.

The two older devices have Touch ID built into the Home button at the front, although the 6S Plus features the second generation of the fingerprint sensor, which is faster and more responsive than the original.

The Apple iPhone 7 Plus is identical in measurement to its predecessor at 158.1 x 77.9 x 7.3mm, but it is a little lighter at 188g. It sports a similar design to the iPhone 6S Plus, but there are a couple of differences, more so than the standard iPhone 7.

Apple has moved the antenna bands across the rear to just the top and bottom edges for a cleaner look and it has also ditched the headphone jack, replacing it with stereo speakers instead. The iPhone 7 Plus is IP67 water and dust resistant and the Home button has also seen some improvements.

That's not all though. The iPhone 7 Plus adds a dual-camera to its rear and two new colours comprising Jet Black and Black have also been introduced. It also comes in Silver, Gold and Rose Gold but not Space Grey anymore.

The iPhone 6S Plus comes in Silver, Space Grey, Gold and Rose Gold colour options, while the iPhone 6 Plus was only available in Silver and Space Grey but has since been discontinued.

The Apple iPhone 6S Plus and iPhone 6 Plus both feature 5.5-inch displays with Full HD resolutions that put their pixel densities at 401ppi.

They are both IPS LCD displays with LED-backlights, but the iPhone 6S Plus also features Apple's pressure sensitive technology called 3D Touch that allows users to do more depending on the force with which they press.

The Apple iPhone 7 Plus also arrives with a 5.5-inch LED-backlit display, but Apple has brightened things up by 25 per cent and added a wide colour gamut to the mix. Resolution remains the same however, so the iPhone 7 Plus offers a 401ppi as its predecessors.

As expected, 3D Touch is on board the iPhone 7 Plus so the experience should be a familiar one to the iPhone 6S.

The Apple iPhone 6S Plus features a 12-megapixel rear camera coupled with a 5-megapixel front-facing camera, both of which feature an aperture of f/2.2. The front facing camera features a Retina Flash and the rear camera is capable of 4K video recording.

The Apple iPhone 6 Plus has an 8-megapixel camera and a 1.2-megapixel front-facing camera, both of which again have an aperture of f/2.2. There is no front flash on the iPhone 6 Plus and the rear camera is only capable of Full HD video recording.

Both the iPhone 6S Plus and the iPhone 6 Plus have optical image stabilisation, but the iPhone 6S Plus also features OIS for video recording too, which the 6 Plus doesn't.

The iPhone 7 Plus changes things up quite significantly in terms of camera. There are two 12-megapixel sensors on the rear - one of which is wide-angle, the other telephoto. The wide-angle lens has an aperture of f/1.8, while the telephoto lens has an aperture of f/2.8. This new setup means the iPhone 7 is capable of optical zoom at 2x and digital zoom up to 10x. 

The iPhone 7 Plus has a number of other features too including a Quad-LED True Tone flash, body and face detection and wide colour capture for photos and Live Photos. The front camera also sees an increased resolution to 7-megapixels with an aperture of f/2.2.

The Apple iPhone 6S Plus features the A9 processor with an embedded M9 motion coprocessor. It offers 2GB of RAM, is now available in storage options of 32GB and 128GB and its battery capacity is thought to be 2750mAh.

The iPhone 6 Plus has the A8 processor with a separate M8 motion coprocessor. There is 1GB of RAM on board and its battery capacity is said to be 2915mAh. Storage options were 16GB, 64GB and 128GB but it can no longer be bought through Apple.

The iPhone 7 Plus arrives with the A10 Fusion processor and it is rumoured to up the RAM to 3GB, though Apple has yet to confirm this. Storage options are 32GB, 128GB and 256GB. The battery capacity for the new device is also said to be an hour longer than the iPhone 6S Plus, though Apple has not confirmed the mAh.

The Apple iPhone 6S Plus and the iPhone 6 Plus launched on iOS 9 and iOS 8 respectively, but they have both seen an update to iOS 10.

There are a couple of software features the iPhone 6S Plus is capable of over the iPhone 6 Plus, such as Live Photos and 3D Touch functions, but the software experience is pretty much the same. 

The iPhone 7 Plus launches on iOS 10 as we mentioned, bringing the new features and functions directly to the new device, all of which you can read about in our separate iOS 10 feature. As the iPhone 6S Plus and iPhone 6 Plus have been updated though, again the software experience should be very familiar, though there will be extra features regarding the camera.

The Apple iPhone 7 Plus offers a number of improvements on both the iPhone 6S Plus and the iPhone 6 Plus, including a whole new camera experience, faster processor, longer battery life (apparently) and a brighter display.

The design has also seen improvements with the removal of the headphone jack, the addition of stereo speakers and the removal of the antenna bands for a more seamless looking device.

Those moving from the iPhone 6 Plus will notice a few more features and enhancements than those considering moving from the iPhone 6S Plus, but all-in-all the iPhone 7 Plus sounds like it will probably be an attractive upgrade for both.