java.util.Vector was introduced with the first version of java development kit (JDK 1.1) and java.util.ArrayList was introduced in java version 1.2 as a part of collections framework, later vector has also been retrofitted to implement List and became the part of the collections framework. Both ArrayList and Vector use array as a internal data structure and are dynamically resizable with default size zero and initial capacity 10.
| S.No | Vector | ArrayList |
| 1. | All the methods in Vector are synchronized | Methods of ArrayList are not synchronized |
| 2. | Vector doubles the size of array when its size is increased | ArrayList increases by half of its size when its size is increased. |