What is the difference between a filler and a discourse marker? There are words that seem fall into both categories.
The Wikipedia article on the latter is sparse and lacks examples, but what it does say on the matter is:
Traditionally, some of the words or phrases that were considered discourse markers were treated as "fillers" or "expletives": words or phrases that had no function at all. [...]
And then goes into linguistic jargon. What is the difference between the two groups? Can the difference be explained to someone without an education in linguistics?