A day after I posted this, I decided to post links to the actual press releases for proof. However, to my surprise, the US press releases are no longer on the Pioneer USA and Canada sites!
Let me begin with the similarities I am aware of. I believe all these players use a form of the MediaTek MT1389 CPU. Pioneer issued a January, 2006 press release for the DV-696AV with a US price of $149.99. Then, while the DV-696AV replaced the DV-585A in the rest of the world, even though the Elite DV-46AV was released in North America, North America was still waiting for the DV-696AV to replace the DV-588A, never notified that it would be released as the Elite DV-46AV with a US price of $299.99 until its release coincided with a June, 2006 press announcement. The noticeable differences were the Elite name, the remote control, and slightly different firmware to accomidate the different remote control. A similar thing happened in 2007 with the DV-600AV and Elite DV-48AV, and 2008 with the DV-610AV and Elite DV-49AV, only in 2007, there were no North American press releases for the DV-600AV and Elite DV-48AV, and in 2008, there were no North American press releases for the DV-610AV and Elite DV-49AV. Yet in 2008, the US price on the DV-49AV dropped to $199.99. I always thought (at least for the 2006 and 2007 models) that North America was paying extra for the Elite name and a special remote control. However, if you compare the Pioneer BDP-LX52 and Elite BDP-23FD 2009 models, it turns out that the Elite version added a beafed-up multi-channel analog output section. This makes me wonder if the 2006-2008 SD DVD situation was similar, and North America was getting a beafed-up analog section. If anyone can answer this, it would solve a very interesting mystery.