Those two arrays are unicode equivalent, but are being represented by different normalization forms. What seems to be happening is that the Java ToCharArray (or string representation) is using one normalization form, while the C# ToCharArray (or string representation) is using another.

This page contains a chart of different normalization forms for Bengali text - the fourth row there describes exactly what you're seeing:

I am only learning about this now, but it seems to me that the motivation for this is so that unicode implementations could remain compatible with pre-existing encodings wherever possible and practical.

For example, one pre-existing encoding may have used a single unicode character, while another pre-existing encoding may have instead used two characters combined. The solution settled on by the unicode folks is thus to support both, at the cost of not having a single "canonical" representation, as you've encountered here.

If you wish for your Java array to be normalized under the "D" normalization form that your C# array seems to be using, it appears that this page provides such a function. You may be looking for something like:

someString = Normalizer.normalize(someString, Normalizer.Form.NFD);

Unicode standard annex 15 is the official document that describes these normalization forms.

You must have entered the string differently.

The text ষ্টোর is Unicode code points 09B7 09CD 099F 09CB 09B0, i.e. 2487 2509 2463 2507 2480, as your C# shows.

The values shown by Java, i.e. 2487 2509 2463 2503 2494 2480, has the 4th character 2507 / 09CB as the two characters 2503 2494 / 09C7 09BE.

Looking them up, they are:

ো ↔ 'BENGALI VOWEL SIGN O' (U+09CB)

vs.

ে ↔ 'BENGALI VOWEL SIGN E' (U+09C7)
া ↔ 'BENGALI VOWEL SIGN AA' (U+09BE)

which combined comes out to the same thing:

ষ্টোর ↔ 09B7 09CD 099F 09CB 09B0
ষ্টোর ↔ 09B7 09CD 099F 09C7 09BE 09B0

They are combining characters, and there are different ways to combine characters to get the same result.