When CD came out, it was basically a digital version of the LP, with a continuous spiral of pits read from the inside out, similarly DVD was designed as a digital video disc, but late in its development acquired the name digital versatile disc as the realisation grew of its potential outside AV. Unlike CD and DVD, MD (and now Hi-MD) was designed to be a general purpose data storage format, with random access like a hard drive. DVD-RAM uses similar technology to DVD, but is a data-based format, which uses the fastest response phase change materials to give the highest performance of all variants of DVD for trick functions, record whilst play, etc.. This is why Panasonic were able to introduce such functions on DVD-RAM first, and whilst DVD-R etc. may appear to catch up, DVD-RAM is always capable of potentially higher performance.
Like DVD-RAM and MD, etc., BD is a data-based format, and the system has been designed to give effectively BD-RAM-like performance with all variants of BD (except for recording on BD-ROM and re-recording on BD-R). However, for the highest speed recording - such as in computer drives, for example, fast response phase change materials as currently used in DVD-RAM may be employed, if required, and such high speed media might be called BD-RAM ...