Nearly identical to the Ruddy Copper Lycaena rubida, and pretty similar on the underside; however, males of the Blue Copper are blue instead of orange above, and females are grayish instead of brown and orange. So, confusion with other Coppers is rare. However, some gray species of Copper (particularly the males) can look similar to the females of the Blue Copper; however, most will have a double row of marginal dark spots below on the front wing, and/or will have a conspicuous orange marginal band on the hind wing below.
On the other hand, confusion with several species of Blues is possible. The Blue Copper is a larger insect than nearly any Blue that may fly with it, and is a bit less "flitting" in it's flight. Most easily confused are perhaps the Silvery, Northern (when there is no orange below), Boisduval's, and the Greenish Blues. The Blue Copper has three dark spots in the discoidal cell (the space near the base of the wing surounded by veins), while only a few species of Blue ever have more than two (and the four mentioned above have only one). Sometimes the third spot (closest to the base) is reduced or rarely absent, and often it is hidden when the wings are folded, but at least two are usually visible. There are other differences between each species that can be seen when the arrangement of the parts of the patterns are compared closely.