Difference between stream and parallelStream in Java

Streams are sequential in nature and process elements one at a time, while parallelStream operates on multiple elements simultaneously using multiple threads.

Using stream is suitable for smaller datasets or when order of processing is important, whereas parallelStream is more efficient for large collections where parallel processing can significantly improve performance.

It is important to note that parallel processing may introduce concurrency issues and the order of elements may not be preserved when using parallelStream.