The key difference between first language and second language is their acquisition. The first language is the language one learns first, and this is usually a natural and effortless process while the second language is the language one acquires after the first language, and this acquisition is usually a challenging process.
Majority of the world population in today’s world is either bilingual or multilingual, i.e., able to speak more than one language. First language and second language are two terms that are mainly relevant to bilinguals and bilingualism. The first language is one’s native language while the second language is the language one acquires later in life.
