Legacy of the elves differed?

On Amazon, there's once the title with a red cover of "the legacy of the elves" and Thalia the "same" only with a gray-blue cover to the Netflix series, there are any differences there?

Maybe different languages?

Do not think that there's a big difference, maybe this is a hardcover and the other paperback? Probably only a newer edition.

Sometimes books are re-released when a series or movie is made about the book, as more people are more likely to be interested in the book. Especially if you print on the cover still the Hinweis that it is the book to the series

the content should be the same

No, these are just two different editions, but the content has remained the same.