Is there a difference between Zen and Zen Buddhism?

exact same thing.
/// i see some are saying its different. i'd ask for their source of information before i'd believe it.
the teachings in Zen Buddhism have frequently been "watered down" by people who are at best just fans of Zen Buddhism(beatnik poets a prime example) and they have called it Zen this or that. usually a cute title like Zen and the Art of (whatever) but there is no difference between true Zen and true Zen Buddhism

They are the same.

Zen is short for Zen Buddhism.

Zen is a Japanese term, borrowed from the Chinese "Chan", meaning "to sit". It describes methodology rather than philosophy. Buddhism traveled from India, through the Himalayas, into China and then into Japan. Along the way it adopted local flavors and customs. So Tibetan Buddhism, headed by the Dali Lama, doesn't look much like Nichiren Zen from Japan. The basic tenets that Buddha taught, the four noble truths, the eightfold path, the illusion of samasara, of separateness, vs. the reality of nirvana, oneness, the need for each individual to explore and question all the teachings for his or her self, are common to most branches and schools, however.

The word 'Zen' was abused by people in secular society looking for marketing new products. Zen Buddhism can no longer be taught in temples, as discussed In the section “Different Levels Have Different Laws” of the Zhuan Falun Lecture on the web.
http://www.falundafa.org/book/eng/pdf/zfl_new.pdf

Guided meditation demonstration video, meditation music, and books about Falun Gong are free to download from the URL listed below. If you need any help, contact a local practitioner in your area for free instructions.

Falun Gong is a unique Buddhist School, found in 1992 by Master Li Hongzhi in China. About 100 million people practice in over 80 countries worldwide. Falun Gong is an ancient practice for the body and spirit based upon the universal principles of Truthfulness, Compassion, and Tolerance. Falun Gong consists of five sets of powerful exercises.

Falun Gong, Tibetans, other Buddhists, and Christians have been persecuted in China. The most offensive human right violation is the organ harvesting from the Falun Gong practitioners in China.
http://www.fofg.org/act/act_appeal.php?a_id=5

Zen is more developing detachment. Indifference to things around one.
Buddhism does to, to an extent. But also teaches us to have rapport with the world around us.

Zen is a lifestyle, while Zen Buddhism is a religion.