The idea seems to be to deliver flagship specs at a lower price point, but when the two devices are so similar it's hard to imagine that they'll both be big sellers.
Nevertheless, the HTC One E8 is here, so if you're wondering just what the difference is between it and the One M8 we've got the answers.
Arguably the biggest and certainly the most immediately noticeable difference between the HTC One M8 and the HTC One E8 is the design.
The HTC One M8 is carved from a single piece of brushed aluminium, which curves into your hand and there's barely a sliver of plastic in sight. It's 146.36 x 70.6 x 9.35mm and 160g.
The HTC One E8 on the other hand is clad in polycarbonate so it looks far less premium than the HTC One M8. However from the front the appearance is similar, as both phones have BoomSound speakers above and below the screen and the sensors and ports are mostly in the same position.
The power key has been shifted from the top right on the M8 to the centre of the top edge on the E8 though.
At 146.42 x 70.67 x 9.85mm and 145g the HTC One E8 is ever so slightly chunkier than the M8, but not enough that you're likely to notice and it's also a little lighter.
There's nothing to choose between the screens. Both phones have 5.0-inch 1080 x 1920 Super LCD 3 displays with a pixel density of 441 pixels per inch.
The two handsets are equally powerful too. They both have a 2.3GHz quad-core Snapdragon 801 processor and 2GB of RAM, so it's safe to say that the HTC One E8 should deliver high end performance.
Once again there's no difference here. Both phones run Android 4.4 KitKat and both are overlaid with Sense 6. That means you'll be treated to the likes of BlinkFeed and Motion Launch whichever handset you opt for.
With the possible exception of the design, the camera is the biggest difference between the HTC One M8 and the HTC One E8.
The M8 has a Ultrapixel sensor and a Duo Camera setup with a second sensor used to judge depth, allowing you to do clever things like changing the focus and blurring the background after a photo has been taken.
The HTC One E8 on the other hand has a far more conventional 13MP snapper. It's debatable whether this is a change for the better or worse as the HTC One M8's Ultrapixel camera is somewhat divisive, but it should mean that the E8 will be able to take more detailed photos but will fare worse than the M8 in sub-optimal lighting.
The HTC One E8 also misses out on the Duo Camera and all the features that come with that but both phones have 5MP front facing snappers and can shoot video in 1080p.
Both phones have a 2600 mAh battery. We were very happy with the performance of the HTC One M8's battery, finding that you could get two days of medium usage out of it and presumably given that the specs are mostly identical the HTC One E8 will have a similarly impressive battery life.
Both the HTC One M8 and HTC One E8 support Bluetooth 4.0, NFC and 4G along with smartphone staples like Wi-Fi, 3G and GPS. In fact seemingly the only difference between the connectivity options is that the HTC One M8 has an IR blaster which the One E8 doesn't appear to.
When it comes to storage the HTC One M8 comes in both 16GB and 32GB flavours while the HTC One E8 comes with just 16GB, but both phones have a microSD card slot which supports cards of up to 128GB.
Right now HTC itself sells the M8 for £549.99, but if you shop around you can get if for just over £500 SIM free, so the most the E8 is seriously undercutting its metal clad brother, not to mention the One Mini 2.
If you don't factor in the price then the HTC One M8 is clearly the superior handset thanks to its premium build.
The camera differences may prove more subjective but wouldn't likely be enough to sway people towards the One E8 if it carried the same price as the M8.
The thing is though, the One E8 isn't just cheaper - it appears to be much, much cheaper. If you can get by with a polycarbonate body and a 13MP camera there's little reason to spend an extra £200 on the One M8.
Of course if it's the best of the best you're looking for in your smartphone, then the M8 is still the clear winner - and it's the only one actually available in the UK at the moment.
- The Samsung Galaxy S5 is clad in plastic too, but that hasn't stopped it selling.