Useful Chart: Compare Anchor and DMC threads by number with this chart from Willow Fabrics.
Over the years I have collected lots of embroidery threads. Each time I started a new cross stitch project I would buy another 15 or 20 skeins of stranded DMC thread so I quickly realised I needed a way to store them. Not only did they need to stay clean for future projects but I didn’t want to be buying a second skein of a colour I already had at home. (Although that has happened at times – I can see a double up in my photo!) My two thread boxes have been perfect. Each box has sections and came with little white thread cards. I simply wrote the thread numbers in pencil and wound on the thread. Then into the boxes in number order. Such a simple system but it works. I only use DMC thread but if you used more than one brand, you could simply add the brand name or the first letter to your numbers.