Two basic color words for different types of blue. You might think of azure, cobalt, and sapphire as shades of blue. To a Russian speaker, синий and голубой are not shades of each other, they are different basic colors, like blue and green in English. And there is no one color word in Russian encompassing all blues.

> To a Russian speaker, синий and голубой are not shades of each other, they are different basic colors, like blue and green in English.

As a native Russian speaker, I always understood "голубой" as a light shade of "синий" (blue), and that's how it's defined in dictionaries [1,2].

[1] https://academic.ru/searchall.php?SWord=%D0%B3%D0%BE%D0%BB%D...

[2] https://ru.wiktionary.org/wiki/%D0%B3%D0%BE%D0%BB%D1%83%D0%B...

Like pink and red? Technically pink is light red, but no one calls it that.

I think pink is less clearly a shade of red (it can go a bit into blue), while "голубой" is simply light or pale blue: AFAICT it's used as an alias, and one may call it "light blue" as well.

just as there is no word in English encompassing all blue-greens