Blu-Ray is a whole different disc format. The way the disc is formatted and read and the compression and everything, they use special blu-ray discs. A dvd that has a 1080p movie on it is just that.....a dvd.
And usually Blu-ray disks are made with more storage than DVDs, so HD movies can take up as much space as they need to, meaning better quality can come as a result.
answering your question a dvd player saying 1080p means it takes the signal from a standard dvd thats at a much lower resolution and upscales it to 1080 progresive. i=interlaced. we have watched all along on tv interlaced progresive is the new hi defintion way to view. blue ray is recorded in 1080p as standard as the disc is able to hold much more data in the video and audio sections giveing u the full impact as mastered
god bless u in jesus name raju