It is very common to find people using the immediate mode. They usually don't know better, and there is a high risk that it is what you will start with if you look for tutorials on Internet. Not that it has to be wrong, but they should know the pros and cons. Instead of explaining the difference everytime, I want to use a link to somewhere with a good explanation, but I can't find any good. There are some snippets here and there in the Wiki, but no good overall summary.
Maybe the Wiki should be extended with a good summary?
Or maybe I simply didn't find a good summary that already exists.