Um... not quite :p
update is what's happening every frame, aka 60 times per second. You don't want to put text draw commands or anything like it into this, unless you know what you're doing, as anything processing-intensive will hugely slow your game down when done every frame.
refresh executes a defined set of commands, like drawing text, on request. For example, at most of the default windows, you'll see a refresh call at the end of initialize - that effectively draws the windows contents for the first time. Now, you can also call the refresh method when the window is already there, for example after your heroes took damage in battle: refresh your window, and you'll see their new health values.