Ahead and Headmost

Ahead adjective - Having the leading position or higher score in a contest.

Headmost and ahead are semantically related In some cases you can use "Headmost" instead an adjective "Ahead".

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

Ahead and headmost are semantically related in lead topic. Sometimes you can use "Ahead" instead an adjective "Headmost", if it concerns topics such as earliest in order.