title: Installing compiled package from .zip file: copy/paste vs. install.packages
body: <p>I just downloaded a .zip file off of Rforge. Is there a difference between installing the package with <code>install.packages("pathtozip",repos = NULL)</code> and just copying the package folder into the R library?</p>
  
  <p>In the past, when I have updated R, I have just copied over the package folders form older versions of R. I am wondering if I need to go back and do a better job getting all the packages installed properly.</p>