The Theravada and Mahayana both accept the Nikayas, however, they have VERY divergent views on the meaning of these sutras.
THE MAHAYANA STATES THE ENTIRE NIKAYAS ARE ABOUT BODIES!!!!
For the Mahayana school (Hevajra Tantra) , the Aghama (Nikayas) means the following :
Nikaya literally means body! Ni-kaya
Samyutta Nikaya = connected body
Madhyamika Nikaya = middling body.
Dirgha Nikaya = Large body.
Anguttara Nikaya = incremental body.
Khuddaka Nikaya - lesser body!
-- within these sutras ---
1) mortal body -- known as the putikaya (putrid decay body) or in Mahayana, Nirmankaya
2) body of marks (32) -- known as sambhogkaya is a transitory body, the body formed due to sacrifice (bodhisatva sacrifice) -- the SACRIFICIAL BODY. It is the revealed body, revealed through self sacrifice.
3) immortal body
-- Dharma kaya - it is the cessation, vajra body.
A normal human being only knows about the mortal body, but is unaware of the Sambhogkaya or Dharmakaya -- which only a Buddhist comes to know of completely.