Chade-Meng Tan summarized here from a talk by Bhikkhu Bodhi (audio talk here):
Most of the records of the teachings of early Buddhism were lost with
the demise of Buddhism in India.
Fortunately, 2 lines of transmission
occurred and survived. The 1st was the Pali Nikayas, which survived
in Sri Lanka via the Theravada school of Buddhism, which thrived
there. The 2nd was the Agamas, which passed from northern India to
Each of these contains 4 collections, with names carrying
largely identical meanings in Pali and Chinese:
- Digha Nikaya (长阿含经), collection of long discourses.
- Majjhima Nikaya (中阿含经), collection of middle-length discourses.
- Samyutta Nikaya (杂阿含经), collection of themed discourses.
- Anguttara Nikaya (增一阿含经), collection of “increase by one” discourses.
The main difference between the Nikayas and Agamas: All the Nikayas
are from the same school of Buddhism, which is the Theravada school.
In contrast, the Chinese translators chose the collection from a
different school for each Agama. For example, they chose the
Dharmaguptaka version of the long discourses, the Sarvastivada version
of the middle-length discourses, and so on. There are some
differences between the nikaya and agama collections. The order of
the discourses are not always identical. Also, some discourses that
are assigned to one collection in the nikayas are assigned to another
in the agamas => assignments are not identical.
You may also be interested in the sub-chapter "3.1 Comparative Studies" from the book "The Authenticity of the Early Buddhist Texts" by Bhikkhu Sujato and Bhikkhu Brahmali.
I quote from it here:
In addition to the full scale study of the Majjhima Nikāya, there have
been multiple smaller studies of various parts of the EBTs. These have
confirmed that all the EBTs share a similar level of agreement to what
we find between the Suttas of the Majjhima Nikāya and its parallels.
Such studies have been carried out for substantial portions of the
Saṁyutta Nikāya/ Saṁyukta Āgamas, and to a lesser extent for the Dīgha
Caution needs to be exercised, however, regarding the Ekottara Āgama,
which is nominally the collection corresponding to the Pali Aṅguttara
Nikāya. Although it shares some significant structural features with
the Aṅguttara, the content is often very different. The text is highly
erratic and internally inconsistent, possibly being an unfinished
draft. Scholars agree that it includes proto-Mahāyānist additions,
thereby establishing its late date of completion compared to the rest
of the EBTs.
This high degree of correspondence among the EBTs across different
lines of transmission does not exist for any other texts of the vast
Buddhist corpus. Even in the stylistically oldest part of the Khuddaka
Nikāya, suchas the Sutta Nipāta, the Udāna, and the Dhammapada, there
is substantial divergence between the schools. This is despite the
fact that these texts do have a common core, which is found across the
different traditions. With texts such as the Abhidhamma, despite a
small common core, the divergence is even greater. But the vast
majority of Buddhist texts are exclusive to the individual schools and
do not have any parallels at all.
This means that the Majjhima Nikaya, Samyutta Nikaya and Digha Nikaya are largely the same between the Pali suttas and the corresponding Agamas.
The Anguttara Nikaya and Ekottara Agama are not the same as the latter has proto-Mahayanist additions.
Meanwhile, the Kuddhaka Nikaya (Sutta Nipata, Udana, Dhammapada etc.) is very different in the Pali suttas and the corresponding Agamas.