One and only and Only

One and only adjective - Eminent beyond or above comparison.

Only is a synonym for one and only in individual topic. In some cases you can use "Only" instead the phrase "One and only" as an adjective or an adverb, when it comes to topics like alone, particularly.

Only adjective - Having no equal or rival for excellence or desirability.

One and only is a synonym for only in sole topic. You can use "One and only" instead the word "Only" as an adjective or an adverb, if it concerns topics such as singular.