title: What is the difference between ArrayBuffer and Array
body: <p>I'm new to scala/java and I have troubles getting the difference between those two.</p>
  
  <p>By reading the scala <a href="https://www.scala-lang.org/api/current/scala/collection/mutable/ArrayBuffer.html" rel="noreferrer">doc</a> I understood that <code>ArrayBuffer</code> are made to be interactive (append, insert, prepend, etc).</p>
  
  <p>1) What are the fundamental implementation differences?</p>
  
  <p>2) Is there performance variation between those two?</p>