great difference
major mistake
本物と偽物では大違いだ。
There's a huge difference between the real thing and a fake.
彼の成績は、前とは大違いを見せた。
His grades showed a great improvement compared to before.
改装後のホテルは、以前との大違いに皆驚いた。
Everyone was surprised by how different the renovated hotel was from before.