QA VS QC :

QA is Quality Assurance and QC is Quality Control.

QA is Process Oriented
Provides suggestions on process improvement
Output of QA is input of QC
EX-Auditing

QC is Product Oriented
Provides suggestions on product improvement
Output of QC is input of QA
EX-Testing

Test Strategy :
The way in which the test will be implemented like top down 
or bottom up..

Top-down - >
main module---sub module---subsub module

Bottom-up - >
subsub module---sub module--main module

QA:In QA we mesure & moniter strenth of the development 
process.
QC:In QC we generally do the validation of final product 
before release to the customer.