Original: Its pear-shaped bell gives it a more covered timbre than that of the oboe, being closer in tonal quality to the oboe d'amore. Whereas the oboe is the soprano instrument of the oboe family, the cor anglais is generally regarded as the alto member of the family, and the oboe d'amore, pitched between the two in the key of A, as the mezzo-soprano member.
Simplified: It is very similar to an oboe, but as it is longer than an oboe it plays lower notes.