Question

What is the difference between oxidation state and coordination number?

Answer 1

Oxidation number is the formal charge present of any metal. But coordination number is the number of ligand (may be negatively charged, neautral, or positively charged) present in the coordination zone.
Formal charge of the central atom may or may not be satisfied by coordinating ligand.
e.g. in [CoCl(NH₃)₅]Cl₂
Here oxidation number of cobalt is +III. This is balanced by three chloride ion one of which is coordinating ligand. Coordination number of cobalt is six (one chloride and 5 ammonia).