Generally field mice are smaller than other mice. There are many different species of field mice and are found all over the world. Field mice normally live in rolling fields or pastures. They tend to eat clover and seeds from plants that grow in this habitat.
There is no difference in a field mouse and a 'house mouse.' Very seldom are there mice in the home in the summer but when it starts to get cold the mice will come in if they can.
The term "field mice" is really a common name for different species of mice that are often found in fields, hence the name. In North America, it refers to a creature called a Meadow Vole.
