Now in my humble opinion, there are many differences between those scriptures preached by the Buddha during the first forty years or so and the Lotus Sūtra, which was preached during the last eight years. However, what scholars consider to be most important, with which I certainly agree, are the concepts of nijō-sabutsu (obtaining Buddhahood by the Two Vehicles) and kuon-jitsujō (attaining Enlightenment in the eternal past.)

First, as for nijō-sabutsu, it is revealed in the Lotus Sūtra that
Śāripūtra is the future Flower Light Buddha (in chapter 3) while Kāśyapa will be Light Buddha in the future; Subhūti, Beautiful Form Buddha; Kātyāyana, Jāmbūnada Golden Light Buddha; Maudgalyāyana, Tamālapatracandana Fragrance Buddha (chapter 6); Pūrṇa, Law Brightness Buddha (chapter 8); Ananda, Mountain Sea Wisdom Buddha; Rāhula, Stepping On Seven Treasure Flower Buddha; two groups of arhats, 500 and 700 in number respectively, Universal Brightness Buddhas; 2,000 of those who have obtained arhatship and those who have not, Treasure Form Buddhas (chapter 9); and female disciples of Mahā-Prajāpatī and Yaśodharā will be Gladly Seen by All Buddha and Emitting Ten Million Ray Buddha respectively in the future (chapter 13).

These people of the Two Vehicles appear to be respected as future Buddhas in the Lotus Sūtra, but are often disappointing in scriptures preached before it, where it is considered that they are unable to ever obtain Buddhahood.

Kaimoku-shō, Open Your Eyes to the Lotus Teaching, Writings of Nichiren Shōnin, Doctrine 2, Page 37-38