In Java, Arrays and Collections both are to deal with a group of objects but there are lots of differences in terms of data structure or performing operations.

Here are some most common differences:

Difference between Arrays & Collections

Arrays	Collections
Arrays is having fixed-length..	Collections are growable in nature i.e increase or decrease.
Arrays are not recommended in terms of memory concerns.	Collections use different data structures and recommended to use with respect to memory.
Arrays are used with respect to performance.	Collections are not recommended to use with respect to performance.
Arrays can store only homogeneous (same type) of data.	Collections can hold both homogeneous and heterogeneous elements.
Arrays do not have a single API.	Collections having big list of methods.
Arrays can work with primitives and object types.	Collections can hold only objects but not with primitive. If you pass as primitive internally convert to object.
See Also: Array & Arrays Class Examples	See Also: Collection Framework and Examples