Does "as sharp as a needle" mean the same as "as sharp as a razor"? Literal and idiomatic
Examples:

The penknife is sharp as a razor / needle.
The old man's senile, but his wife is as sharp as a razor / needle.

Question

Does "as sharp as a needle" mean the same as "as sharp as a razor"? Literal and idiomatic
Examples:

The penknife is sharp as a razor / needle.
The old man's senile, but his wife is as sharp as a razor / needle.

Answer

There's really no difference.

If I thought about it, I'd think 'The penknife is sharp as a razor' implies that the point of the penknife is sharp (just like a needle), while the entire blade of the penknife is sharp if it's sharp like a razor. 
Honestly, I doubt many people would think into it this far.

Metaphorically, there's definitely no difference.

Đừng bỏ lỡ cơ hội học ngoại ngữ ngay tại nhà. Hãy xem danh sách các gia sư ngôn ngữ giàu kinh nghiệm của chúng tôi và đăng ký buổi học đầu tiên ngay hôm nay!