From the Python FAQ:
Lists and tuples, while similar in many respects, are generally used in fundamentally different ways. Tuples can be thought of as being similar to Pascal records or C structs; they’re small collections of related data which may be of different types which are operated on as a group. For example, a Cartesian coordinate is appropriately represented as a tuple of two or three numbers.
Lists, on the other hand, are more like arrays in other languages. They tend to hold a varying number of objects all of which have the same type and which are operated on one-by-one.
Generally by convention you wouldn’t choose a list or a tuple just based on its (im)mutability. You would choose a tuple for small collections of completely different pieces of data in which a full-blown class would be too heavyweight, and a list for collections of any reasonable size where you have a homogeneous set of data.