However, in both cases, there were also lots of other types. For instance, the epaulets were just plain boards (similar to the last picture).
You know, at first, I thought the epaulets are the ones that are more fancy but then I noticed that people use them quite interchangeably. Moreover, Wikipedia says both words are equivalents + offers other 3 words with the same meaning: a shoulder mark, rank slide and slip-on.
My question is, is there any difference in appearence between the epaulet and shoulder board?