title: Difference between pip install . and pip install -e
body: <p>I have created a package in python, and now I would like to install it as a regular package. 
  What is the difference between just using <code>pip3 install .</code> and <code>pip3 install -e .</code> ? </p>
  
  <p>The reason why I asked, is because with pip3 install . the package, although installed was not seen by the system. While in the second way it was working fine</p>