For the most part we can define ‘neo-advaita’ (or radical non-duality) as those teachings/communications that state all is already one/whole and there is no separate individual self, and as there is no separate self, there can be no useful practice as all practices reinforce the notion of an individual self that is carrying out the practice; therefore, according to neo-advaita, there is no path to liberation, no practice that can help one attain liberation, and no separate self to be liberated, and to say the contrary is fine but inaccurate.
This is in contrast to traditional-type Advaita teachings that for the most part acknowledge all is already one, but often state there is some kind of process or path that one can engage with and engaging with this teaching and path will in some way help ‘you attain direct realisation/liberation’ of the oneness/Self that is already present. Sri Ramana Maharshi explains this more fully here.
Which view is correct?
I think most seekers that have explored this can see the potential benefits of both approaches, but most neo-advaita types reject the practice/progress orientated paths, and vice versa.
My own view is that the neo-advaita types for the most part have only a very superficial realisation and they also do not usually point to suffering ending (unlike traditionally orientated paths), but that does not make neo-advaita entirely worthless of course, as different things resonate at different times in our journey.
I have written several posts on this which may be of interest to you, best wishes: