Number one and One and only

Number one noun - The first or highest in an ordering or series.

One and only and number one are semantically related In some cases you can use "One and only" instead a noun phrase "Number one".

One and only adjective - Eminent beyond or above comparison.

Number one and one and only are semantically related in someone adored topic. Sometimes you can use "Number one" instead a noun phrase "One and only".