The understanding is belief and saving faith aren’t exactly the same thing. Belief is having knowledge and acceptance of the knowledge. Understanding the Jesus claimed to be Lord is knowledge, agreeing that Jesus is Lord is Belief (the kind the Demons have).
Faith is more than just belief. Faith is belief+trust. Knowledge is seeing a chair, belief is agreeing that it can hold your weight, faith is sitting in the chair. So to say Faith alone doesn’t mean Faith without works. Faith includes works.
Edit- I came across this quote from J.D. Lightfoot who was an Anglican Bishop in the 19th Century.
“Faith is not an intellectual assent, nor a sympathetic sentiment merely. It is the absolute surrender of self to the will of a Being who has a right to command this surrender”