a tagger size kit is used to make signatures and blinkies and web art. The elements look the same as a "full kit" when you are viewing them online. The difference comes in with the resolution and when you want to print your pages/images.
full size kits are typically made at a resolution of 300 dpi and tagger sizes I think are made at 72dpi (for web images). If you are going to be printing your layouts, you will want the full sized kits