Historically, the Bahá'í Faith has its foundation in the Bábí religion. So much is owed by the Bahá'í Faith to the religion of the Báb that the Bahá'í teachings sometimes describe the two religions as one and the same.
Shoghi Effendi feels that the unity of the Bahá’í Revelation as one complete whole embracing the Faith of the Báb should be emphasized... The Faith of the Báb should not be divorced from that of Bahá’u’lláh. Though the teachings of the Bayan have been abrogated and superseded by the laws of the Aqdas, yet due to the fact that the Báb considered Himself as the Forerunner of Bahá’u’lláh, we would regard His Dispensation together with that of Bahá’u’lláh as forming one entity, the former being introductory to the advent of the latter.
Letter written on behalf of Shoghi Effendi,
Preface to the Kitáb-i-Aqdas
But it's much more than that. To better understand the historically subordinate position of the Bahá'í Faith with respect to its catalyst, the Báb, we should look at how well the Bahá'í Faith retained Bábí doctrine. The Báb, though certainly an extremist, managed to effect more change in several years than Bahá'u'lláh did over several decades.
The Bahá'í Faith uses the Bábí calendar, which has its starting date in the year of the declaration of the Báb. When Bahá'ís think of the first Bahá'ís, they think of the Bábís.
An astonishing amount of Bahá'í laws and practices reflect their Bábí origins, but even some aspects of Bahá'í belief and practice that are regarded as original to the Bahá'í Faith were established during the Bábí period. The abrogation of holy war is a chief example.
The Bábí rebellion ceased long before Bahá'u'lláh assumed any leadership role in the movement, and it was Subh-i-Azal, the official and well-recognized leader of the Bábís, that officially ended the practice of holy war by the Bábís. Continuing to permit holy war would most certainly have meant only more oppression of the Bábís, and after all, abrogating holy war was no great change from the Báb's teachings. The Báb was no general and no war monger. He forbade unnecessary carrying of arms and conversion by force. He appeared to condone the Bábí rebellion as much as encourage it. It was anticlimactic, to say the least, for Bahá'u'lláh to declare that he was abrograting holy war four decades after the end of the rebellion (Lawh-i-Bishárát, 1891). It wasn't much of a change either, as Bahá'u'lláh endorsed the use of arms in self-defense and in international disputes (when internationally mandated).
The Báb made several important changes with respect to the status of women. He forbade the wearing of veils, forbade concubinage, and discouraged polygyny (while allowing men to have two wives). Bahá'u'lláh adopted the two latter changes in his law, though he did have three wives, one of whom was legally a concubine. As for the wearing of veils, he appears to have silently adopted the Bábí law.
The following is a general listing of Bábí laws and ordinances (etc) retained by Bahá'u'lláh: