Buddhism is practiced in many countries by many different peoples. How do Buddhists in America differ in their beliefs, values Buddhism is practiced in many countries by many different peoples. How do Buddhists in America differ in their beliefs, values, rituals, practices etc? Or, is Buddhism fairly uniform wherever it is practiced?
The transmission of Buddhist teachings to the United States (and the West in general) can be described in three general categories: migration, appropriation, and adoption. The last category is, in my opinion, the most interesting to explore, but for sake of completeness, let's discuss the other two first.

Migration

The most direct and obvious transmission of Buddhism to the US is through the immigration of practitioners from Buddhist majority countries. As these communities grew, they established temples. These temples are largely a direct continuation of whatever tradition the immigrants adhered to. As a result, a wide variety of Buddhist traditions have some representation in the US.

Appropriation

I acknowledge that "appropriation" is a loaded term. I have no intent to demean or antagonize anyone, but I do feel the word adequately describes how some Americans have borrowed specific Buddhist practices while ignoring the rest.

In particular, mindfulness meditation is following a path similar to yoga. When Western psychologists studied meditation extensively, they discovered genuine, tangible, scientifically verifiable benefits for practitioners. Mindfulness meditation is now being promoted and even prescribed as means of improving mental and emotional health, much in the same way that a doctor might recommend yoga as a form of exercise.

The beliefs of such practitioners would be difficult to summarize as there is presumably little that ties them together. It would be like asking about the personal beliefs of weight lifters or tennis players; the only common thread is an appreciation for a shared activity.

Adoption

The third category of American Buddhists are those who've adopted the teachings as a supplement or (more likely) an alternative to predominant Judeo-Christian traditions. Though these individuals are often white and educated liberals, the truly unifying factor is their shared appreciation of what makes Buddhism distinct from other major world religions and a desire for spiritual enrichment. These distinct elements tend to be emphasized in the beliefs and practices of what I refer to as "American Buddhists."

It's worth noting that the communities of American Buddhist practitioners vary considerably. I have personally seen everything ranging from a small group of college kids with little knowledge or connection to the large Sangha to temples with clear, official ties to existing Asian schools. (An example of the later is the Rochester Zen Center in Upstate New York.)

Some of the beliefs and practices that are more unique to American Buddhists include:


Personal Practice: Americans generally adopt Buddhism as a means to personal moral and spiritual growth. Many are isolated or in small communities and have limited knowledge of the varied traditions within Buddhism. As a result, many practitioners are apt to emphasizes practices aimed towards individual growth - particularly those suited for novice, lay practitioners. There is a general belief that the true value of the practice is the tangible effects it has on practitioners.
Secularism: Mainstream religious traditions in the US tend to promote literal interpretations of the bible quite vigorously, even when in direct confrontation of established science. Buddhism is seen as a more "science friendly" religion and thus attracts those who are skeptical of or completely reject the existence of the supernatural. As a result, American Buddhism handles concepts such as reincarnation, karma, and merit as metaphors.
Egalitarian Communities: The ratio of ordained to laity among American Buddhists is significantly skewed towards laity when compared to Asian countries. It's no surprise, then, that communities often rely on lay people to operate. However, this is also in part a reaction to how heavy-handed mainstream religious communities can be with authority. American Buddhists value ordained members for their wisdom, experience, and dedication, but won't necessarily expect them to assume all leadership responsibilities. 
Engaged Buddhism: American Buddhists are quite likely to adopt Engaged Buddhism where they are actively involved in charity, politics, and society at large. There are numerous reasons for this. First, anyone who choose to adopt a "foreign" religion are apt to be free thinkers willing to challenge societal norms that they disagree with. Second, Americans generally believe that one's values should be expressed through action; someone who chooses to withdraw from the world is likely to be seen as apathetic, cowardly, or insincere. Third, American Buddhists don't have the advantage of being part of an established majority; they are more likely to find themselves at odds with majority opinion and may feel compelled to act in order to protect and preserve their values. Forth, values such as empathy and compassion are arguably lacking in American culture so there are many instances of personal or institutional greed, intolerance, and apathy to address. 


Naturally, these are all generalizations based on personal experience. I am not aware of any research to understand how the beliefs of those who adopted Buddhism compares to those of Asian Buddhists.



For more on this subject, see my answer on Quora to: How is American Buddhism different from the different versions of Buddhism in Asia?