Iterator Spliterator
It performs only iteration. It performs splitting as well as iteration.
Iterates elements one by one. Iterates elements one by one or in bulk.
Most suitable for serial processing. Most suitable for parallel processing.
Iterates only collection types. Iterates collections, arrays and streams.
Size is unknown. You can get exact size or estimate of the size.
Introduced in JDK 1.2. Introduced in JDK 1.8.
You can’t extract properties of the iterating elements. You can extract some properties of the iterating elements.
External iteration. Internal iteration.
https://javaconceptoftheday.com/differences-between-iterator-vs-spliterator-in-java-8