It's been a year since Apple announced the iPhone 6 and its bigger brother the iPhone 6 Plus, which only means one thing - the 'S' version of these two devices are now here, taking over as the latest and greatest iPhones. Or the "most advanced smartphones in the world" according to Apple.

As this is an 'S year', there wasn't any expectation for a dramatic change to the design, because that just doesn't fit how Apple does things. But while the design remains the same, Apple did make a fair few changes to the new iPhone 6S and iPhone 6S Plus, perhaps surprising some. Here are five new features the Apple iPhone 6S and Apple iPhone 6S Plus bring with them.

3D Touch displays on Apple iPhone 6S and Apple iPhone 6S Plus 

Force Touch is a term that has been knocking about for a while now after Apple introduced the pressure-sensitive haptic technology to its Apple Watch and the new MacBook. Huawei has also been playing with the term, launching it on the 128GB model of its Mate S smartphone at IFA in Berlin last week. The iPhone 6S and iPhone 6S Plus didn't go for a Force Touch display, but something similar called 3D Touch instead.

Force Touch technology knows how light or hard you are pressing or tapping the screen to open up an all-new level of interaction. For example, on the Apple Watch, pressing harder on the watch face will allow you to change it, while a soft tap does nothing. On the iPhone 6S and iPhone 6S Plus however, a hard press will bring up shortcuts.

Pressing with force on the camera app icon will bring up a "Peep" menu, allowing you to select a frequently used feature, such as launching the selfie camera for example. You can read more about it in our 3D Touch feature.

New camera on Apple iPhone 6S and Apple iPhone 6S Plus

Apple's iPhones have been consistently praised in the past for having decent smartphone cameras, despite having less megapixels than their competition. Apple has finally upped its megapixel game for the iPhone 6S and iPhone 6S Plus, as well as introduced 4K video capability.

The cameras on the new iPhones see a jump to 12-megapixels for the rear and 5-megapixels for the front, which although is still lower than the competition, there are a couple of exciting additions to the camera aspect. Live Photo is a feature that will automatically snap 1.5-seconds before a shot has been taken and 1.5-seconds after, allowing you to "play" the image on an Apple device after the moment to relive it. 

Additionally, Apple has made the Retina display on the front of the iPhone 6S and iPhone 6S Plus double up as a flash so now your selfies should be even better.

Upgraded processor on Apple iPhone 6S and Apple iPhone 6S Plus

With every new iPhone comes a new processor and the iPhone 6S and iPhone 6S Plus comes complete with the new A9 chip and M9 motion coprocessor. Unlike the previous iPhone, the motion coprocessor has been integrated into the A9 chip, which means it will always be on and therefore always monitoring your movements. Touch ID has also been improved.

An upgraded processor should mean the usual, such as better handling of tasks, better battery life perhaps and where the motion coprocessor is concerned, better activity tracking and movement sensing. Apple claims the A9 chip is 70 per cent faster in terms of CPU and 90 per cent faster in terms of GPU compared to the A8 chip.

iOS 9 for Apple iPhone 6S and Apple iPhone 6S Plus

Just as dark clouds bring rain, a new iPhone brings new software and in the case of the iPhone 6S and iPhone 6S Plus - it's iOS 9 that makes its debut. The software was previewed at WWDC in June and it will bring with it several new features when it arrives on 16 September for current iPhone users, or 25 September for those after the new iPhones.

Siri will have an all-new user interface and interact with your iPhone in a more in-depth way, with pro-active features and suggestions based on your phone's location. It has also been merged closely with search, which has also seen some dramatic improvements and Passbook will be renamed to Wallet, to name but a few.

Apple iPhone 6S and Apple iPhone 6S Plus design

Although we mentioned previously that the design remained the same on the new iPhones, Apple did announce a new colour for the iPhone 6S and the iPhone 6S Plus and the aluminium has also been changed.

The new colour is going by the name of rose pink and the aluminium being used for the iPhone 6S and iPhone 6S Plus is the same 7000 series used in the Apple Watch.