Headmost and Highest

Headmost adjective - Coming before all others in time or order.

Highest and headmost are semantically related. in order topic. In some cases you can use "Highest" instead an adjective "Headmost", when it comes to topics like chief.

Highest adjective - Being at a point or level higher than all others.

Headmost and highest are semantically related. Sometimes you can use "Headmost" instead an adjective "Highest".