US? UK? USSR?
New York? Chicago?


In the US and Canada typical colors would be white, black, red and green/bare. If you are in Chicagoland conduit is typical and you will see many other colors.

Most likely the blue is the hot and the white is the neutral. Without a meter/tester and the knowledge of how to use it you are only guessing and taking a safety risk.
Do you have a meter? Without one you should NOT be doing ANY electrical work.

US - California. The confusing part is that the old light was paired the black wire in the old light to the white in the ceiling and the brown on the old light (possibly once white) to the blue.