I read a lot of the reviews before making a purchase and decided on both black tights to see the difference between the two. Purchased both in Medium size.
I am Australian size 10-12 in pants. eg Rockwear/Running Bare/Lorna Jane type gym legging I would be size 12 but Kmart/Kathmandu pants or trousers size 10.
The ones named "Wintergear Yoga Pants(xyp83) - Black" are my preference, they are soft and perfect for cold days lounging around the house but also dressy enough fabric to wear to the shops with a nice jumper. They are high waist (above my belly button and I'm 165cm tall) the fleece lining is soft and warm enough on their own but would also be thin enough to be a good base layer. They do NOT have a side pocket but they do have a small key pocket inside the waist.
The ones named "Wintergear Yoga Pants(xyp84) - Black" are a bit more stiff and I found the thigh area a bit tighter and more difficult to get on. Due to the tightness they didn't go as high in the waist but would still be a high waist style. These are definitely a more sporty look with the seams running all over and leg pocket. The fleece lining is the same in both so I will prefer to use these as more active style leggings for walks or runs in winter, or again would be a good base layer with waterproof trousers.
Colour: Wintergear Yoga Pants(xyp83) - Black | Size: X-Small Promotions can vary depending on colour/size.