Pick, Chris,
Assuming what you are trying to ingest (green tea, Pomegranate) to achieve some level of efficacy, I think its simply an issue of dosing - the extract will clearly be a higher dose, whether or not that has a better clinical effect is not clear, however most studies when they try to examine the efficacy of these products will use the extract, thus I would best the pharmacokinetics are better for the extract?
Make sense?