In terms of the weight of the yarn, 12 Ply yarn is commonly referred to as Chunky Yarn, so in terms of the weight yarn, yes 12 Ply is the same as Chunky. It is also commonly known as Bulky yarn in the USA, which incidentally has its own numbering system for describing the thickness, or weight, of yarn. 12 Ply Yarn, also known as Chunky yarn, is referred to as #5 in this American system. For more information, please refer to our article Yarn Weight Comparison Chart.