Highest and In high spirits

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

In high spirits and highest are semantically related. In some cases you can use "In high spirits" instead an adjective "Highest".

In high spirits adjective - Happy and excited and energetic.

Highest and in high spirits are semantically related. Sometimes you can replace term "Highest" with "In high spirits", this terms are similar.