WATERCOLORS - A three-ply hand-dyed pima cotton in variegated colors. It has a silky sheen, especially when used with long, flat stitches. Separate the plies and use one or more in the needle according to the pattern directions. One ply is about the same weight as a #5 pearl cotton or six plies of cotton floss or one ply of persian wool. 

WILDFLOWERS - A single strand hand-dyed cotton in variegated colors. It has more of a matte finish when stitched. Use one or more strands as required by the ground fabric. One strand is approximately the same weight as flower thread or Medicis wool. It is between a #8 and #12 pearl cotton in weight. It is available in all the same colors as Watercolours and the two threads can be used very successfully together for hardanger embroidery. 

Descriptions from Caron website.