Difference between Data Type and Abstract Data Type?

Answer 1

A data type tends to mean a primitive data type. Primitive data are built-in data types, such as integers, characters and Booleans. They are basic constructs of the language (that is, they are built into the language).

Primitive data also tends to be of a strict data type, meaning you can't treat characters like integers or Booleans like integers, etc., although some languages will support implicit casting of primitive data types (for example, will treat Booleans like integers if you use a Boolean in an arithmetic operation).

Abstract data types are generally constructed by the user or by a higher level language. For example, you might create a currency data type, which generally acts like a float but always has a precision of 2 decimal places and implements special rules about how to round off fractions of a cent.

Abstract data types also often contain the ability to either be treated as a specific type of primitive data in certain circumstances (for example, many languages allow you to treat strings as character arrays); or contain certain rules / methods to manipulate their data (such as a programming language allowing you to cast a float as an integer).

A data structure is a gathering together of many different data types. For example, objects and arrays are data structures. Data structures usually can contain information of many different types (such as strings, integers, Booleans) at the same time, and in more complex structures -- namely, classes -- can contain specific methods, properties and events to manipulate that data, change its type, etc.

Answer 2

One is bigger than the other. Your teacher wants more than this for an answer so you need to study this.