What is the difference between contribution margin and gross margin?

contribution margin that comes from managers and departments like travel expenses , car , water gas etc. gross margin is    all margin before  shrinkage .  

Contribution margin is the difference between Sales & Variable cost; Sales - Variable cost=Contribution

Gross margin is the difference between sales & Cost of goods sold ;Sales-COGS=Gross Margin

The exact difference is in  Gross margin calculation   consideration will give to all cost to make sales.