One of the biggest differences between these two denominations is, to put it succinctly, "how wet you get" at baptism. Baptists accept only baptism by immersion, while Methodists tend towards the "sprinkling" method of baptism.
Both Baptist and Methodist denominations have similar governing organizations and methods of worship.
Baptist and Methodists are very similar. As Baptist we practice Baptism by total immersion. We will make an exception, however, when the one to be Baptized is bed-ridden, or is physically impaired so as not to be able to enter the Baptistery. Since Baptism is only an outward expression of an inward experience, the method is really not that important. The act of Baptism does not send any one to heaven, nor does the lack of it send anyone to hell. We practice total immersion because Jesus did. He was baptized by John the Baptist.
Since Baptism is not necessary for salvation, the Methodist have chosen as a more convenient method, sprinkling. There is nothing more to be gained or lost by either method.
There are other subtle differences between Baptists and Methodists. The theology is pretty much the same. Methodist pastors may or may not wear robes when they preach. Normally Baptist pastors will wear street clothes, most likely a suit and tie. The Methodists have governing bodies, usually consisting of the title of Bishops of the Church. Baptist governing bodies are generally Deacons.
Baptists tend to be more theologically conservative than Methodists; not merely concerning issues of baptism, but also pressing social issues in the US, like homosexuality. Many Methodist congregations are becoming more accepting of homosexuality and woman as ministers, etc. Baptists tend to be more 'fundamentalist' in their understanding of scripture and certainly more socially conservative.
Baptist is a term describing individuals belonging to a Baptist church or a Baptist denomination. The name is derived from a conviction that followers of Jesus Christ are commanded to be baptized (by being immersed in water) as a public display of their faith, and thus most adherents reject infant baptism. While the term "Baptist" has its origins with the Anabaptists, and was sometimes viewed as pejorative, the denomination itself is historically linked to the English Dissenter or Separatist or Nonconformism movements of the 16Th century.
Baptists are typically considered Protestants. Some Baptists reject that association. Most Baptist churches choose to associate with denominational groups that provide support without control. The largest Baptist association is the Southern Baptist Convention but there are many other baptist associations.
Both Roger Williams and his compatriot in working for religious freedom, Dr. John Clarke, are variously credited as founding the earliest Baptist church in America. In 1639, Williams established a Baptist church in Providence, Rhode Island, and Clarke began a Baptist church in Newport, Rhode Island. According to a Baptist historian who has researched the matter extensively, "There is much debate over the centuries as to whether the Providence or Newport church deserved the place of 'first' Baptist congregation in America. Exact records for both congregations are lacking."
Methodism is a movement within Protestant Christianity represented by a number of denominations and organizations. The Methodist movement traces its origin to the evangelical awakening in 18Th century Great Britain. Methodism followed from the work of John Wesley, who was an Anglican clergyman. Thus "Methodism" is commonly taken as "Wesleyan Methodism". Wesley sought to keep Methodism as a revival movement within the Church of England, and a significant number of Anglican clergy were known as Methodists. Other 18Th century branches of Methodism include Welsh Methodists, later the Calvinistic Methodists, from the work of Howell Harris, and the Countess of Huntingdon's Connexion through the work of George Whitefield. The influence of Lady Huntingdon and Whitefield on the Church of England was a factor in the establishing of the Free Church of England in 1844. Through vigorous missionary activity Methodism spread throughout the British Empire, the United States, and beyond.
Early Methodists were drawn from all levels of society, including aristocracy. But the Methodist preachers took the message to laborers and criminals who tended to be left outside of organized religion at that time. Wesley himself thought it wrong to preach outside a Church building until persuaded otherwise by Whitefield.
Doctrinally, the branches of Methodism following Wesley are Arminian, while those following Harris and Whitefield are Calvinistic. Wesley did not let this difference of interpretation change his friendship with Whitefield, and Wesley's sermon on Whitefield's death is full of praise and affection. Methodism has a very wide variety of forms of worship, ranging from high church to low church in liturgical usage. The Wesleys themselves greatly valued the Anglican liturgy and tradition, and based Methodist worship in The Book of Offices on the 1662 Book of Common Prayer.
In 2006, Methodism claimed some seventy-five million members worldwide.