"Functionalities" vs "features" - what's the difference?

A feature is a prominent characteristic or something added as a special attraction. One product has many features which we can generally separate into two groups: the different things it can do, and the different UI attractions.

The functionality of a product usually means the extent of its overall ability:

2. The purpose that something is designed or expected to fulfill
- manufacturing processes may be affected by the functionality of the product

3. The range of operations that can be run on a computer or other electronic system
- new software with additional functionality

However, it can sometimes mean the same thing as function, (i.e. one ability, as opposed to overall ability). From the free dictionary, note definition 2:

1. The quality of being functional.
2. A useful function within a computer application or program.
3. The capacity of a computer program or application to provide a useful function.

"It is important to remember the distinction between product functions and product features. Functions are the “product’s answer to the set of user tasks”; features are the “user tools” inherent in the product used to perform the functions (Wood, 1995). Placing a telephone call is a function; the dial tone and the touch-tone keypad are features used to accomplish the function. Product Types have different sets of functions, and each Model within a Type accomplishes its functions through potentially different features." http://inclusive.com/mmr/findings/functions_and_features.htm