Just like last year, Motorola is preparing multiple Android handsets to be sold under the flagship Moto X brand, a person who was briefed on the plans told VentureBeat.

The two all-metal phones look similar enough that images of them — leaked yesterday by HelloMotoHK on Google+ — were widely reported to be of a single device. While there are many internal and external differences between the so-called Vertex (pictured left) and Vector Thin (pictured right), they share one important attribute: compatibility with an ecosystem of modular, swappable backplates that endow the phones with significant additional functionality.

Interestingly enough, we got a look at their design way back in December, with a leak whose veracity was widely questioned at the time, but which turned out to be a very accurate depiction.

Sleek and powerful

Both models feature 5.5-inch AMOLED displays, but otherwise, their spec sheets read completely differently, according to the person who shared the details. Vector Thin is the decidedly higher-end handset, with a Quad HD resolution to Vertex’s Full HD display, and a slightly lower-clocked version of Qualcomm’s Snapdragon 820 system-on-chip (2.0GHz quad core) to its sibling’s Snapdragon 625 (an octa core chip reportedly clocked at 2.4GHz instead of the stock 2.0GHz).

Vector Thin will ship with 32GB of storage capacity in conjunction with either 3GB or 4GB of RAM, while Vertex will allegedly come in either 16GB storage / 2GB RAM or 32GB storage / 3GB RAM configurations. Camera configurations are also said to differ. Vertex purportedly sports a 16-megapixel sensor with both laser-assisted and phase detection autofocus technologies, while Vector’s 13-megapixel sensor has only the laser AF, but with optical image stabilization thrown in too.

Externally, the only major difference, as its name suggests, is Vector Thin’s incredibly svelte profile: at 5.2 millimeters thick, it’s even slimmer than Vertex’s already respectable thickness of about 7mm. As you might suspect, Vector’s thinness comes at the price of reduced battery capacity: It contains just a 2600mAh cell, compared to the 3500mAh pack in the less-pixel-dense Vertex.

Modular done right

The bigger story here starts with those 16 holes seen on the back of the white Vertex, above. While they’ve been written off in some coverage as speaker ports, they are actually connection pins that allow modular backplates to be snapped onto either handset.

Motorola has at least six modules, called “Amps,” planned for launch, including a simple colored backplate that ships free with both handsets. The more interesting ones will be, of course, sold separately, both from Moto as well as third-party manufacturers. The first-party modules available at launch allegedly include stereo speakers; a battery pack; a camera grip with flash and optical zoom; a pico projector; and a rugged cover with wide angle lens attachment.

It should now be clear that the phones’ protruding camera lens will actually sit flush when there are Amps attached. They’re connected magnetically in a manner that was said to make for a tight, secure connection while also allowing for easy removal.

This modular system, and the one introduced by LG with the LG G5, are undoubtedly similar and will prompt comparisons in the press. And despite being first to market, LG is very likely going to come out on the losing end of these evaluations. Focusing so tightly on offering a removable battery seems to have hamstrung the Korean manufacturer into a form factor not nearly as well-suited for the task as Motorola’s.

While pricing and release details aren’t yet known for the Moto X pair (nor their likely doppelgängers on Verizon, the Droid Turbo 3 and Droid Maxx 3), the date on the renders, August 24, may prove significant. [Update: Droid-Life is reporting that these will launch on June 9th at Lenovo Tech World.]