Stephen Lam / Reuters The five colors of the new iPhone 5C are seen on screen at Apple's media event in Cupertino, Calif., on Sept. 10, 2013

Meet the two newest members of Apple’s iPhone family: a much faster, fully 64-bit iPhone 5S and the iPhone 5C, essentially a tweaked iPhone 5 available in multiple colors. Both phones will launch simultaneously on Sept. 20. Apple revealed the phones during a press event at its corporate campus in Cupertino, Calif., on Tuesday afternoon.

Apple claims the iPhone 5S is up to twice as fast for both CPU and graphics and says the new A7 processor housed within includes over a billion transistors — twice as many as the A6 processor in the iPhone 5, while retaining the same footprint (iOS 7 has apparently been updated to take advantage of the new 64-bit architecture too). The iPhone 5S will be available in black, gold or silver colors.

The iPhone 5S also includes something Apple calls an M7 motion co-processor, which keeps tabs on the device’s accelerometer, gyroscope and compass. Apple says this will enable new types of health and fitness apps, like a new Nike+ Move app that keeps track of how active you are.

As expected, the iPhone 5S will include a touch ID fingerprint sensor built into the home button. It’ll scan fingerprints in any orientation as well as subdermal fingerprint layers, and Apple noted you can use it to unlock your phone without a PIN or make iTunes purchases without entering a password. Lest you worry that data’s being stored in the cloud, Apple confirmed it’s not backed up or stored on Apple’s servers, and that it’s encrypted and locked within the A7 chip — it’s not directly accessible by software.

Camera-wise, the iPhone 5S’s aperture is slightly larger than the iPhone 5’s, the f-number dropping from f/2.4 to f/2.2 (lower is better). It’ll also do auto image stabilization, allowing you to take multiple photos at once and combine the sharpest parts of each. You can now operate in Burst Mode (hold the shutter to snap up to 10 frames per second) or use a SloMo camera app that lets you shoot video at up to 120 frames per second at 720p.

To demonstrate the power of the iPhone 5S, Apple brought Epic Games onstage to announce and then show off Infinity Blade 3 — apparently the conclusion of Epic’s mobile action-strategy trilogy — with up to eight worlds on tap.

While Apple didn’t delve into specifics about the A7’s 64-bit architecture, the 64-bit shift typically allows computers to access more than 4 GB of memory. That’s not something Apple needs today, but there’s a theory that Apple’s laying the groundwork for much more powerful iPhones and iPads. With the A7 chip, Apple is kicking off that transition now, so it won’t have to keep supporting a 32-bit operating system in a few years.

The iPhone 5S looks to be priced in line with prior models: $199 for 16 GB, $299 for 32 GB or $399 for 64 GB — all with two-year cellular contracts.

The iPhone 5C, by comparison, includes Apple’s older (but still powerful) A6 processor, an 8-megapixel camera, polycarbonate casing without seams or cracks, a higher battery capacity than prior iPhones and availability in multiple colors, including white, blue, yellow, red and green. It includes a front-facing FaceTime HD camera capable of taking sharper pictures, and will sell for less than the iPhone 5 originally did: $99 (16 GB) or $199 (32 GB) with a two-year contract; Apple’s listing the unlocked pricing for the iPhone 5C on its website as $550 (16 GB) and $650 (32 GB). Colorized custom cases will sell for $29, and the cases have holes in the back, allowing you to create a two-tone look if you prefer.

Internally, the iPhone 5C seems similar to the current iPhone 5, with some improvements to battery life and front-facing camera quality. The main differences are the external design and the availability of a $200 32-GB version, which previously hasn’t been available in lower-tier iPhone models. It’s still unclear what the off-contract price will be.

Both the iPhone 5S and 5C will ship with iOS 7, which has a flatter, more modern look than previous versions, and adds major new features. For instance, users can swipe up to reveal a quick-settings menu called Command Center, and send photos directly to other iOS devices and Macs using a feature called AirDrop. Apple said iOS 7 would be available for free starting Sept. 18 for existing iPhone 4 (and up), iPad 2 (and up), iPad Mini and fifth-generation iPod Touch users.

Interestingly, the iPhone 4S is still alive: Apple will continue to sell an 8-GB model that’ll be free on contract, so it seems it’s just the letter-free iPhone 5 that’s dying here.

When can you preorder the new iPhones? Apple confirmed Sept. 13 for the iPhone 5C; the iPhone 5S will be available in store (as will the 5C) and for order on Sept. 20.