Question: is l2 acquisition the same as l1 acquisition

Answer: No, Adults who learn a second language differ from children learning their first language in at least three ways: children are still developing their brains whereas adults have mature minds, and adults have at least a first language that orients their thinking and speaking. Although some adult second-language learners reach very high levels of proficiency, pronunciation tends to be non-native. This lack of native pronunciation in adult learners is explained by the critical period hypothesis. When a learner's speech plateaus, it is known as fossilization.