Enchanted Item is a term that covers any item that has, through the use of magic, been improved or altered in some way. This ranges from the few examples of enchanted items given in the GMG, to even simple enchanted items that player characters can create (the ritual versions of the spells Grasp, certain variants of Radiance, Aegis, The Labourer Abides, Second Sight, Scrye, Animate and History all create permenantly enchanted items of some sort or another).
Karmic Item is a term that covers all items that, due to the circumstances of their creation, their history or some other factor, are imbued with karmic energy. This often comes to pass when sentient beings - especially humans, who practically exude karma on a regular basis - use such items regularly and for important tasks. In essence, the emotions of the acts they're involved in lodge on an item and make it Karmic to some degree or another. This isn't just abstract energy either, but actual memory and emotion, which is why Dragons and Scions are so eager to find their own Hoards (which consist of Karmic Items), as their lives and memories are imprinted onto the items they have hoarded.
An Enchanted Item is valuable - it does something special and unusual that makes people desire it and wish to possess it. That strength of emotion can, over time and given suitable intensity, lead to an Enchanted Item being Karmic as well.
In short, Karmic Items and Enchanted Items are two different things... but they are not mutually exclusive. An item can be Karmic without being enchanted, and can be Enchanted without being Karmic, but could also be both Karmic and Enchanted.