I haven't had my hands on either Archos model, but I can tell you that these are some very basic ereaders. They have incomplete support for Epub and limited annotation options. Luckily they do also offer some limited ability to play video and audio, so if you like you could use one as a media player.
Back in late April Archos started shipping the 70d ereader, a minimalist device with a cheap 7" screen and a decent amount of storage and format support but no Wifi or touchscreen. I have it pictured at right, and if you've read this blog for a while you might recognize it.
When I reviewed the 70d it went by the name Slick ER-701, and it's now the Polaroid ER-701. And it's not just a similar looking device; I found a review of the 70d and not only does the ereader look like mine it also uses the exact same menus and displays ebooks in a way that looks identical.
I wasn't terribly impressed with the ER-701 at the time, but I've since had a number of readers report that it's not bad for a $30 to $40 ereader. I still disagree; I still think a tablet would be a better buy. Or if you're planning to buy 2 devices, I'd pool the funds and get a better tablet.
Now, the other new Archos ereader just showed up on Amazon.co.uk yesterday. It has a 9" screen, and aside from having some buttons moved around it is pretty much the same ereader as the 70d.
I haven't had my hands on this one, but from all appearances it looks to be a close relative of the one of the Polaroid ereaders that i saw at CES 2012. Some buttons have been moved around, but aside from that I'd bet it's the same ereader.
I don't believe it ever hit the US market, though.
In case you're interested, I know the 7" ereaders are the same device because of the general similarity in hardware design as well as the fact they use the same menus. That tells me that the devices were originally developed by Gajah, a Singapore based ereader company.
They've had a bunch of their designs show up under a number of different brand names. Line all those rebranded devices in a row and I'm pretty sure that Gajah would turn out to be one of the most widely distributed ereader manufacturers . They also make a few Android tablets, but it's been a while since I saw any of those, either.