The difference between NCERT and SCERT is that NCERT does not provide a detailed description of a topic or a lot of examples related to it, whereas a detailed description of a matter is found in SCERT.
In NCERT, questions are rotated slightly whereas in SCERT, the label of questions is simple and straightforward.
In NCERT, you can get to see many such examples, which are not mentioned clearly in the book.
In short, if I say, no topic in NCERT is as detailed as it is in SCERT. Therefore it is necessary to take recourse to both.