With the exception of using console.log to print what's received from a request and response.write to echo a request back, these two seem to essentially do the same thing (echo data back to me). Thanks in advance!
console.log puts the data on the standard output (file descriptor number 1).
response.write write the data on the response object, whatever it is. In your case it seems to be a response to an HTTP request, but it may be any other stream (including standard output).
The results of both of those commands can end up in the same place - like your screen - but taking a different path to the same destination: console.log doesn't use the network in the process but response.write (most likely) does. I say "most likely" because it is not clear from your question what this response is a response to.