>>26495486Since Pokemon Special is a monthly series in Japan, currently running parts are initially cut up into mini-volumes so that they don't have to wait half a year between new issues. Once the part finishes, they go back and re-release the entire series in proper 200 page volumes, like Japan gets.
In Japan, the like 5 or so chapters of HGSS and the first 4 chapters of BW were in the same book. Viz decided that was confusing and just made the last volume of HGSS longer and the first volume of BW shorter. As a result, the re-released version of volume 1 (left) ended up the same length as the original mini-issue (right).