Currently, all varieties of mild and hot peppers (not to be confused with black and white pepper derived from Piper nigrum and related species) are considered as the fruits of Capsicum annuum and its many varieties, or of 2 species, C. annuum and C. frutescens. Current practice is to classify the pungent varieties of pepper (chile peppers or cayenne peppers) as C. frutescens, and the milder-flavored sweet peppers (bell peppers, sweet peppers, green peppers) as varieties of C. annuum; however, most botanists agree that they should properly be regarded as varieties of C. annuum.
C. annuum and C. frutescens seems to be different species as in the later the calyx teeth are absent. Moreover, the later species bears more than 1 flower in each node but the former species bears single flower per node, in general. The fruit size of C. frutescens is smaller than that of C. annuum, irrespective of the varieties.