Examine the bush. Currant bushes can grow up to 5 feet high and about that wide. If the plant is a currant bush, it should appear to be a "clump" of many different stems.
Check the leaves of the bush. Currant bushes have alternately-spaced leaves (they are not opposite each other on the stem). The leaves should appear similar to that of a maple. They are lobed, with toothed edges. The black currant bush has pale green-colored leaves while the red currant bush has a deeper greenish-bluish shade.
Examine the flowers of the bush. Currant bushes flower in the spring. Currant bush flowers are bell-shaped and yellowish-whitish. They grow in a row, alternately-spaced.
Check the bush for currant berries if you have positively identified the shrub as being a currant bush. Unripe currant berries are green, whether they are black or red. The berries grow in a cluster, or a chain. Red currants are a reddish color and tend to ripen all at once. Black currants are a darker purplish-brownish color and tend to ripen from the top downward.