Do "声优" and "配音演员" mean the same thing?
声优 is a loanword from Japanese. 配音演员 is Chinese original. They mean the same thing: voice cast. So usually 声优 refers to Japanese voice actors of Japanese animations. Chinese voice actors are rarely mentioned as 声优. But you can call a 声优 as (日本动漫)配音演员. So the usage of 配音演员 is more general, while 声优 is almost always  Japanese related.
Who is famous is opinion based and out of the range of this forum.