3D Touch is a new feature found in iOS 9 on the iPhone 6s and iPhone 6s Plus. It uses Apple's Taptic Engine and pressure sensors to sense the amount of pressure you apply to your display. A light touch, for example, allows you to preview things like emails, photos and even directions in Apple Maps. Users can also apply more pressure to "pop" open emails, Maps and more. You can fine-tune the amount of pressure it takes to perform a "peek and pop" transition by navigating to Settings > General > Accessibility > 3D Touch.
Force Touch is found on the Apple Watch and current MacBook products, Touch 3D is only available on the iPhone 6s and iPhone 6s Plus. They both use Apple's Taptic Engine and pressure sensors to work, but they perform different tasks. Force Touch replaces the right-click option on a MacBook. On the Apple Watch it allows users to brings up additional controls in apps, such as the Messages and Music apps.
As expected, Apple today revealed the iPhone 6s and iPhone 6s Plus. The next generation iPhones have been completely revamped. CEO Tim Cook described the iPhone 6s as the "most advanced smartphone in the world". First off, externally the iPhone 6s models feature a custom aerospace 7000 aluminum alloy developed by Apple. In addition to the existing colors, a rose gold model will join the lineups.