Note: The Imaging Pedals should be shipping about now, so I'm waiting to hear some user reports:
My understanding is that the pedals are a sub-set of the Aura Blender. The Blender includes a lot more Aura Images, and also has the capability to download new Aura Images (via a MIDI connection though.)
And then there's also the Ellipse Aura, which can be installed inside your guitar (the controls are accessible through the sound hole of the guitar.)
So you have three products to choose from. This is how I see the differences (but am interested to get other's take on this.)
i] The Blender gives you the most options and you can install custom images. It's much larger than a pedal though. It's best for those that have multiple models of guitar they'd like to play through Aura.
ii] The Imaging Pedals are much smaller than the Blender, so convenient for performing. If you have multiple guitars of the same body size, then that's great. If you want to use two different body sizes (a dread and an OM) then you might have to get two pedals (though you might be happy with the way the OM pedal sounds with your dread or vice versa.) Cons: Two pedals cost as much as the Blender, and are almost as bulky, so if you're thinking of getting more than one pedal you should probably get the Blender.
iii] The Ellipse Aura mounts inside the guitar. You can download custom Aura Images, so you can set it up for the guitar. Less hassle than pedals. Cons: If you have more than one guitar it becomes expensive.