A "Seventh-day Adventist" is a member of an Adventist denomination distinguished chiefly for its observance of the Sabbath on Saturday. They’re a member of that branch of the Adventists which constituted itself as a separate body after the expected Second Coming of Christ failed to be realized in 1844. They are strongly Protestant; believe that Christ's coming is imminent.
The Seventh-day Adventist Church (abbreviated SDA) is a Christian denomination that grew out of the prophetic "Millerite" ) movement (i.e. William Miller in the United States during the middle part of the 19th century. It considers itself a branch of Protestant Christianity, though differences in doctrine and practice have led some mainstream Christians to dispute that designation.
The name of the Seventh-day Adventist denomination shows its two main distinctive characteristics: Sabbath observance on the seventh day (i.e., Saturday) and an expectation that the end of the world is drawing near. Other unique characteristics include adherence or devotion to the teachings of Ellen G. White (who is regarded as a prophet), and various dietary observances rooted in Jewish law.
In latest buzz, as his surge in heavily evangelical Iowa puts a spotlight on his faith, Republican presidential candidate Ben Carson is opening up about his membership in the Seventh-day Adventist Church. Find out more at Miamiherald.com.