A Partial Answer Behind Why Some PS3 Games Need to Install

[kenzomatic]

The issue arises from differences in the reading techniques of DVD and Blu-ray. By nature, the outer and inner parts of a disc move at different speeds while a disc is spinning, regardless of format (CD, DVD, Blu-ray, HD-DVD, etc.). While DVD drives can read data at those differing speeds, Blu-ray reads at one speed. Combine that with the extremely large size of Blu-ray discs, and simply dumping existing DVD data onto a Blu-ray disc will inevitably result in longer load times.

He would seems to be saying the load time would not be the same.