Diff between "join" and boolean "union"?

 From:  Michael Gibson
1689.5 In reply to 1689.4 
I guess the key thing to stress here is "individual surfaces".

If you have created 2 or more surfaces that are totally independent objects but have been arranged to be sitting right next to one another, that's when you use Join to glue them together.

For everything else, you use booleans.

- Michael