There may be differences among some manufacturers using these terms, but generally speaking a power distribution unit provides multiple outlets without any significant filtering for noise reduction. Power conditioners usually have some mechanism for filtering and removing noise from the powerline, and some also provide a degree of isolation between the outlets. Power conditioners can be passive in design using mostly capacitors and inductors to filter and isolate, or active regenerators which create a clean power sinewave from a DC power supply. Some active conditioners also use passive filters to provide individual filtering and isolation between outlets. Each design type has its advantages and proponents as well as some limitations.
I will ask a dumb question on power conditioners
....what is the difference between a power conditioner and a power distribution unit ???? I saw the site for these here on Audiogon and I noticed that there are in fact two types of units being sold. 40 years in this hobby and I understand power conditioners....but what is the difference and what are each used for ????