Quality Assurance:
-------------------
1)Process Oriented 
2)Defect Prevention 
3)Proactive

Quality control 
------------------ 
1)Product oriented  
2)Defect Detection   
3) Reactive

QA: QA involves monitoring and improving entire SDLC 
process,making sure that any agreed upon standards and 
procedures are followed and problems are found and dealt 
with. It is oriented to "Prevention".

QC: QC is the process of Inspections, walkthroughs and 
Reviews.

Quality assurance         Quality control
  -----------------         ---------------
1.Process oriented          product oriented
2.Defect prevention         Defect Deduction
3.Minimize defect           To deliver zero defect product
4.Collecting user           Apply test against standards 
requirements

QC:It involves activity to fulfill & verify the requirement of quality. it follow company standards.

QA: In QA we assure the customer that quality of Software product is in accordance with as expected by customer. During QA we don't follow company standard instead we perform different testing.