Without getting too technical, the simple way to explain the differences is to compare the two with your everyday home VCR. So called “normal” Time Lapse recorders use the “standard” also referred to as the “2hr. mode” for it’s reference speed, whereas the “HD” unit is based on the “EP/SLP mode” or the “6 hr. mode”. Therefore the “HD” recorders offer approximately three times more recorded information than compared to it’s “normal” cousin.
The disadvantages to this is the picture quality is noticeably poorer than that of “normal” Time Lapse recorders. And when this is digitized in any way it is even more noticeable.
So the choice is yours …more pictures and less picture quality, or better quality pictures and less pictures!