There are many Buddhist sutras. The sutras are mostly the words of Buddha. There are also a few that are spoken by great disciples. Then there is, in addition, a literature on the discipline for renunciants called the Vinaya and a philosophical literature written soon after the death of Shakyamuni called the Abhidharma. In addition, there are commentries written by the great ancestors of the Buddhist tradition. These include many hugely important original works such as the Senchaku of Honen Shonin, the Shobogenzo of Dogen Zenji and the Transmission of the Lamp by Atisha. The total literature is vast.
Consequently each school of Buddhism has its favoured scriptures from within the whole. Some schools favour the Nikayas. Some favour the Lotus Sutra. The Purealnd Schools favour the Pureland Sutras and so on. In Amida we favour the Pureland Sutras, but also the Lotus Sutra and take the whole range of Buddhist literature as an important resource.
The word ’sutra’ means a ‘thread’. When you have a surgical operation, they stitch up the wound with ‘sutures’. It is the same word spelt differently. So each sutra speaks to a theme or thread of conversation, which brings out the fact that the majority of sutras started out as memories of significant conversations, particularly conversations between Shakyamuni and an enquirer.
All these threads tell us some aspect of the Dharma, but as the different people that Shakyamuni talked to were diverse and had diverse concerns, so the conversations went different ways. Hence there are many threads.
Now, of course, this means that were you yourself to encounter the Buddha there could ensue a conversation that would then give rise to a new sutra, one especially tailored to your particular case or koan. Everyone should make a prayer to hear that sutra.