What is the relationship between Annie and Andy in English?

The two have nothing to do with each other.

Anne comes from Hannah, an ancient Hebrew word, which means "He loves me".

Andy is Andrew's nickname, which comes from the ancient Greek word Andreas, meaning "man".

English, belonging to the West Germanic branch of the Germanic family of Indo-European languages, evolved from the languages spoken by Germanic tribes such as Anglo-Saxon and Jute who immigrated to the British Isles from Germany, Holland and Scandinavia in ancient times, and spread to all parts of the world through active British colonization. Due to contact with many national languages in history, vocabulary has changed from unitary to pluralistic, grammar has changed from "more inflections" to "less inflections", and pronunciation has changed regularly.

According to the number of native English speakers, English is the official language of the most used countries, the most widely used second language in the world, and the official language of the European Union, the most international organizations and Commonwealth countries. The number of native English speakers ranks third in the world, only after Chinese and Spanish.