Detergents contain a vast array of "fillers" and various agents that are designed to ensure that they disperse properly and can be flushed out of the dispensor drawer effectively.
The Proctor and Gamble tablet have a combination of two chemicals which start to release gas (CO2 or Oxygen) when water is added. The tablets litterally start to fizz and disintegrate in the drawer.
To be quite honest, I can't see the point of detergent tablets. It's much easier and more environmentally friendly to use a scoop and powder!
Likewise, liquid detergents don't make a lot of sense in front loading washing machines unless you're adding it to the dispensor drawer. The drawer automatically dilutes, disperses and helps to disolve the detergent and ensures that it's evenly distrubuted throught the wash and that it starts having an impact on the laundry from the start.
Adding detergent in a ball or putting tablets into the drum in a low-water consumption washer can only make the wash results worse as they will remain undisolved for a signifigant amount of time and won't be distrubuted around the load quickly enough.
For the most part these balls, liquids, tablets and other dosing methods are simply markting gimics to improve sales.
Also, on the issue of High Efficiency detergent. In the UK (and I assume throughtout Europe) we really have no alternatives to what you guys call HE detergents, except for a couple that are specifically designed for handwashing.
In the 1970s the low-foaming detergents were called "Automatic" e.g. Persil Automatic, Daz Automatic, Ariel Automatic. Non automatic detergents were for use in semi-automatic toploading twin tub machines and for handwashing only.
So, I'm not even sure if you used a US-style toploader here if you could source appropriate detergent as the products available here are all designed for tumble action front loading machines