What are the main technical differences between a DVD player and a Blu ray player?

DVD uses a red laser to read and write data, while Blu-ray uses a blue-violet laser. The blue-violet laser (405nm) has a shorter wavelength than a red laser (650nm), which makes it possible to focus the laser spot with even greater precision. This allows data to be packed more tightly and stored in less space, so it's possible to fit more data on the disc even though it's the same size as a CD/DVD. This together with the change of numerical aperture to 0.85 is what enables Blu-ray Discs to hold 25GB/50GB.

1. A blu-ray player adds a blue laser. That allows them to read higher density, IE more capacity.

2. The processor system is stronger, both to decode the HD video used, and for the advanced interactive features used on Blu-Ray discs. Some players even have network connections to connect to the internet to download/stream online content or from your computer.

basically blu ray discs have a larger capacity than a dvd disk, meaning that more data can be stored on a blu ray disk, so movies will be of higher quality with less compression. But really the differences are quite minimalistic in my opinion.

both are actually disc players, but Blu-ray players have the extra capability to play Blu ray discs which provide better video and audio quality compared to DVDs.

the amount of data on the discs.

the size of the lazer (bluray is much smaller)