QA - Quality Assurance this is a parellel Process While developing the 
application Testing should done.
QC - Quality Control is a completed process simply used for maintain the clients 
give the solution and should reproduce the faced bug in our lab

Qa is an umbrella like activity that spans across all the
phases in a SDLC. it means QA ensures the project is going
in right direction are we building the product in right way

ex : reviews, walktrhoughs, audits

QC is a actual validation of the requirements and confirm
that application meets the requirement are we building the
right product
ex : unit testing, uat testing

QA means quality assurance
Defination:To measuring and monitoring the devolopement 
strength process(or)Defect detection and prevention methode.

QC quality control
Defination:Developement team delivered build testing
(or)Defect detection and correction methode.
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QA-Quality Assurance-Set of activities involved in the 
entire SDLC to improve the quality of the product.
Prevention of the bug in the application.

QC-Quality control- Detect and correct the bug in the 
application.
 Working with the application in a controlled environment 
to validate the application.