の違いを

the difference between

→ の
phrase Rare #39,337
the difference between の connects the preceding noun to 違い (“difference”), and を marks it as the object of the verb that follows.
JA: 二つの方法の違いを説明します。
EN: I’ll explain the difference between the two methods.

紅茶と緑茶の違いを私に説明できますか。

Can you explain the difference between black tea and green tea to me?

ミッキーのパーティーで世界の違いを思い知った

At Mickey’s party, I really saw just how different the world can be.

— グッドフェローズ (1990)

トムはイラクとイランの違いを知らない。

Tom doesn't know the difference between Iraq and Iran.