Have you looked at the VBE Help for details on each of the methods?
Having said that, you will generally find that your code runs much better by using neither method. It is rarely necessary to either Select or Activate an object in order to work with it. In fact, doing so just makes your code slower.
For example, using your objective of copying, if we used the Macro Recorder we would get the following code:
However, we could obtain the same objective by removing the Select elements of the code (and specifying the destination argument). Like this:
Does that help?