is Zero knowledge Proof same as commitment schemes?
"is Zero knowledge Proof same as commitment schemes?"

No, although if one makes soundness be only computational

(i.e., arguments rather than proofs) , ​ then existence of such zero-knowledge protocols

is equivalent to existence of instance-dependent commitment schemes.



"How can prover A prove that he is in the possession of some value 'X'

without disclosing 'X' to B. 'X' could be A's last name or A's telephone number"

How would the verifier check validity of the claimed 'X' if A did disclose 'X' to B?

Your hashing remark suggests that what you're thinking

about is actually proving knowledge of a preimage:

i.e., both parties know 'Y', and A is proving knowledge of a 'W' such that ​ H(W) = Y .