What Is The Difference Between Norco And Vicodin Tablets?

Hello cvs no longer carries my medication Vicodin 500 and 5 acetami they gave me norco 500 and 325 ace..and I feel weird. My insurance did not pay for new vicodin 500 and 300 It that had worked in the past without making me feel strange.
I want to nring back medicine and change it for old..will I have a problem..what is the difference between Norco and vicodin,,my stomach is upset and hard to sleep