Bound Field
The Bound field is used to bound the value of a field as text value .Only for displaying text we are using bound field.In bound field we can't do customerization as like template field.Say for example we can't edit the data's when you binded using bound field.
Template field
The Template field used well in customization. Which can be used when editing the value of the data after grid bind.The Template field more flexible than Bound field. Also in Template field we can bind our own asp controls.