What exactly was the difference between Alara Kalama & uddaka rāmaputta teachings?
The two teachers are in the Ariyapariyesana Sutta.

Alara Kalama taught to focus on 'nothingness' and Uddaka Ramaputta taught to enter the 'dimension of neither perception nor non-perception'.

Both meditations are only mental stillness &amp; quiet and do not uproot the causes of suffering. The the 'dimension of neither perception nor non-perception' is very close to unconsciousness. They can only bring temporary peace, which is why the Buddha rejected them. They are not freedom. The Buddha discovered true freedom is having no craving, no attachment and no self.