In several ways. That is an oversimplified definition, and not the best one. Panentheists don't believe in a transcendent personal God, so that immediately rules out religions like Christianity, Islam, and Judaism. There is the more traditional German idealist (Hegelian) form and there is the more modern process (Whiteheadian) form of panentheism. Neither one posits a "God" in any traditional faith sense or involves any form of worship. It is rather a philosopher's god. It is more of an admission, or rather an assumption, that there may be something more to nature, or beyond nature, that can be explained by nature alone and generates the laws of nature as we know them. Something more akin to the Elan Vital, or creative energy of Henri Bergson.
The only real difference between Pantheists and Panentheists, as far as I can tell, is that Pantheists would say that this creative energy is inherent to nature itself, while Panentheists would place this creative energy as a prime mover of nature.