title: Is there a difference between "brew install" and "pip install"?
body: <p>I want to install pillow on my Mac.  I have <code>python 2.7</code> and <code>python 3.4</code>, both installed with Homebrew.  I tried <code>brew install pillow</code> and it worked fine, but only for <code>python 2.7</code>.  I haven't been able to find a way to install it for <code>python 3</code>.  I tried <code>brew install pillow3</code> but no luck.  I've found a post on SO that says to first install <code>pip3</code> with Homebrew and then use <code>pip3 install pillow</code>.  As it happens, I have already installed <code>pip3</code>.</p>
  
  <p>I've never understood the difference, if any, between installing a python package  with <code>pip</code> and installing it with Homebrew.  Can you explain it to me?  Also, is it preferable to install with Homebrew if a formula is available?  If installing with Homebrew is indeed preferable, do you know how to install <code>pillow</code> for <code>python 3</code> with Homebrew?</p>
  
  <p>The first answers indicate that I haven't made myself plain.  If I had installed pillow with <code>pip install pillow</code> instead of <code>brew install pillow</code> would the installation on my system be any different?  Why would Homebrew make a formula that does something that <code>pip</code> already does?  Would it check for additional prerequisites or something?  Why is there a formula for pillow with <code>python2</code>, but not as far as I can tell for <code>pillow</code> with <code>python3</code>?     </p>