There's a world of difference between him and that actor.
He and that actor are at opposite ends when it comes to their popularity.
この場合、次のような言い方ができますよ。
ーThere's a world of difference between him and that actor.
「彼とその俳優は天と地の差がある」
There's a world of difference で「天と地の差がある」と表現できます。
ーHe and that actor are at opposite ends when it comes to their popularity.
「彼とその俳優は人気になると天と地の差がある」
to be at opposite ends を使っても「天と地の差がある」ことを表現できます。
ご参考まで！
カナダ 
