Mennonite and Amish beliefs are based upon the same simplicity of faith and practice as lived by the early Christan church.
The difference between the two groups is how the beliefs are practiced and lived. The overall doctrine followed by each is similar.
The Mennonites tend to be more tolerant of technology and the outside world than are the Amish. The Mennonites accept higher education and modern technology. They tend to see these influences as ways that can be used to strengthen their religious beliefs.
The Amish, on the other hand, tend to feel that these influences of the outside world only interfere with the purity of their faith. They generally forbid higher education, dress in "plain" clothes, refrain from the use of electricity and ride in horse-drawn buggies.
The Mennonites have historically sought to increase their fellowship through missionary activities throughout the world. Whereas, the Amish have never felt the need for such activities.
Perhaps, the best way to understand the Anabaptist heritage in Lancaster County is not to distinguish between the Amish and the Mennonites. Rather, it is more helpful to differentiate between the the "Old Order" and the "Modern."
Old Order Amish and Old Order Mennonites are those who base their lifestyle decision-making choices from their faith fellowship and tradition. These are the Amish and Mennonites who dress "plain," forbid higher education, ride in horse and buggies, and choose occupations connected to the farm and to the home.