Differences between Second Language Learning and First Language Acquisitio

Acquiring a second language can be a lifelong learning process for many as the second language learners are rarely successful. However, children by around the age of 5 have more or less mastered their first language with the exception of vocabulary and a few grammatical structures.

Read this interesting article at this link
http://www.languageinindia.com/nov2011/shinefirstsecond.pdf