The Array question type further extends the List question type. Using this question type, a matrix can be displayed where the left column is represented by a sub-question, while each row is represented by the same set of answer options. The text of the question can be either a specific question or a description.
In terms of output there is no difference in how responses are stored compared to List (Radio) question type. The given answer is stored in a separate column in the result table for both question types.
The most flexible array types are Array, Array (Text) and Array (Numbers)'. However, LimeSurvey also supports a number of array types which have predefined answer options (e.g., Array 5 point choice).