The main difference basically is Champion Japan own their design and product team which can produce their own line. They aim for quality and original retro style for the trend nowadays , so they use better quality and wider choices of fabric like Reverse Weave...etc
What is Reverse Weave: Most Sweatshirts, especially inexpensive ones, stitch vertically because it’s faster and more cost-effective to stitch in one straight line. However, after listening to the concerns of the coaches about shrinkage when washing big batches of athletic wear, Champion decided in 1934 to go against the grain, literally, and stitch their athletic gear with a more time-consuming but superior transverse method which was cut on the cross-grain. There is nothing that will affect the structure and construction of the T-shirt or sweatshirt after the updated method; a testament to Champion’s pioneering of Reverse Weave—shrink resistant, durable, and made to last.