ECP's and PP's

 Hi everybody,
 I have just read the interesting summary by Dale Braden in the CCL on ECP's.
 One of the questions he raised in his original posting was whether there is
 a difference between "effective core potentials" and
 "pseudopotentials". To
 my limited knowledge, there is none. But maybe one of the experts could
 comment on this question? -- I couldn't find a definite answer in the mentioned
 summary. So my question is, what -- if any -- is the difference between PP's
 and ECP's?  Just curious ...
 Thanx, Georg
 P.S. I will summarize to the list if there are any answers.
 Georg Schreckenbach                      Tel: (Canada)-403-220 8204
 Department of Chemistry                  FAX: (Canada)-403-289 9488
 University of Calgary                    Email: schrecke : at :
 2500 University Drive N.W.,  Calgary,  Alberta,  Canada,  T2N 1N4