Surgical knife and Surgical instrument

Surgical knife noun - A very sharp knife used in surgery.

Surgical instrument and surgical knife are semantically related. In some cases you can use "Surgical instrument" instead a noun phrase "Surgical knife".

Surgical instrument noun - A medical instrument used in surgery.

Surgical knife and surgical instrument are semantically related. Sometimes you can replace phrase "Surgical knife" with "Surgical instrument", this phrases are similar.