Tom, the difference is basically one of user interface.
With a few DVD/hard disk recorders--such as the TiVo-based Humax DRT800
, as well as at least one non-TiVo deck, Philips's HDRW720
--any time you're watching TV via the device, you can just press Pause and Rewind, or Fast-forward afterward, to control "live" TV. With DVD recorders such as the Pioneer and the Panasonic DMR-EH50
, you must manually press Record first or already be watching a timer recording. Then you can go into a menu or press a button (Play on those two decks) to go into Chase Playback mode, which is basically the same thing, allowing you to pause, rewind, and fast-forward back to real-time. As someone used to DVRs, I prefer TiVo's "always-on" method, but perhaps Pioneer wanted their recorders to behave more like a VCR and figured always-on recording would confuse users. Also, with TiVo/Humax/Philips, the HDD is always spinning and can cause wear and tear, although in my experience, DVR hard drives last a very long time.