Firsthand and First-string

Firsthand adjective - Done or working without something else coming in between.

First-string and firsthand are semantically related. In some cases you can use "First-string" instead an adjective "Firsthand".

First-string adjective - Of the very best kind.

Firsthand and first-string are semantically related. Sometimes you can use "Firsthand" instead an adjective phrase "First-string".