Signal Processing algorithms in a modern Blu-Ray Player MIGHT be significantly better than those in the HDTV. You also MIGHT see a noticeable difference if you switch between a Blu-Ray Player's HDMI and Component Video Output Interfaces, since these algorithms might not be applied the same on each Interface, for example HDMI Output MAY OR MAY NOT be a direct bit-for-bit stream read off the DVD, bypassing the Blu-Ray's Signal Processor and thereby relying solely on the algorithms in the HDTV.
Here is a description of the advanced Signal Processing algorithms in my pricey OPPO BD-93 3D Blu-Ray Player:
and a description of other similar algorithms and why they are needed:
You should be able to track down a generalized description of the algorithms in YOUR Blu-Ray Player....I'll bet they're much better than her old DVD Player....
And of course, there will be a big jump in PQ when playing Hi-Rez Blu-Ray discs...although not quite as good as on a 1080p HDTV....