My understanding is that there's 1080p upscaling (or upconversion), which Blu Ray players can do but DVD players do not. Consequently, DVDs often look a little better played on a Blu Ray player than on a standard DVD player.
Which makes no sense at all, nor is it true.
A (European/PAL) DVD is 720x576 pixels with a pixel aspect ratio of 1,42 -> 1024x576.
Every time it is played on a HDTV, it is upscaled. Otherwise it would not fill the screen that has 1920x1080 visible pixels. And it doesn't matter where the upscaling happens, whether it happens in the TV or the DVD player.
Blu ray players are no different. They get 720x576 pixels and upscale to 1920x1080. Done. The most common upscaling filter is Bicubic, followed by Bilinear. The differences are marginal. There is no magical CSI algorithm that adds new information that magically makes a DVD image sharper than it actually is. Yeah, they can run an additional Sharpen filter, but every
TV, DVD player or blu ray player has that option.
Upscaling is upscaling, it doesn't matter where it happens. TVs scale 480i, 576i, 576p and 720p signals up by default. So does a blu ray player.