What is the difference between QC & QA?

QA vs QC is always an issue in our industries..
to summarize QA is proactive and QC is reactive meaning that QC aims to identify defects in the finished product, in the bulk before releasing and in the rm when received but the QA should preset a system to follow in which to prevent to have any defect.
QC find and alert on a specific problem, the QC should investigate, assess, improve and rework the process to prevent repetition of any problem.

I would like first to emphasis the important of Quality control enviroment in any Organization, in addition such Methodology and standards will enhance & raise-up reputation & BRAND of any Organization: Quality Assurance: A set of activities designed to ensure that the development and/or maintenance process is adequate to ensure a system will meet its objectives.
Quality Control: A set of activities designed to evaluate a developed work product.
Testing: The process of executing a system with the intent of finding defects.
(Note that the "process of executing a system" includes test planning prior to the execution of the test cases.) QA activities ensure that the process is defined and appropriate.
Methodology and standards development are examples of QA activities.
A QA review would focus on the process elements of a project e.g., are requirements being defined at the proper level of detail.
In contrast, QC activities focus on finding defects in specific deliverables - e.g., are the defined requirements the right requirements.
Testing is one example of a QC activity, but there are others such as inspections.

QA includes all the Procedures, Work Instructions, Tools (eg.
Statistical Process Control) which aims the process and developed to prevent defects in the product.
On the other hand; QC includes all the inspections, tests, techniques or activities used to identify defects in the product

WHAT IS THE DIFFERENCE BETWEEN QC & QA? Let us first understand Quality, Assurance & Control QUALITY: Quality as “the degree of excellence of a thing ”.
From the customer’s perspective , quality is “ Fitness for use” - how well product or service does what it is supposed to The dimensions of Quality are : Performance, Features, Reliability, Conformance, Durability, Serviceability, Aesthetics, Safety, Perceptions, time and Timeliness, Completeness, Courtesy, Consistency, Accuracy, Accessibility & Convenience, Responsiveness.
ASSURANCE : The act of giving confidence, the state of being certain or the act of making certain.
CONTROL : An evaluation to indicate needed corrective responses; the act of guiding a process in which variability is attributable to a constant system of chance causes.
QUALITY ASSURANCE is a system : An overall management plan to guarantee the integrity of data QUALITY CONTROL : A series of analytical measurements used to assess the quality of the analytical data Quality Assurance: The planned and systematic activities implemented in a quality system so that quality requirements for a product or service will be fulfilled.
Quality Control: The observation techniques and activities used to fulfill requirements for quality QA aims to prevent defects with a focus on the process used to make the product.
It is a proactive quality process.
QC aims to identify defects in the finished product.
Quality control, therefore, is a reactive process.
Quality Assurance developed from the realisation that quality could be improved by looking 'further up the line'.
It is aimed at preventing nonconformities/defects.
QA still has QC at its core to control the quality of service/product, but it goes beyond mere testing or inspection to also consider related activities or processes (such as training, document control and audits) that may be resulting in defects further down the line.
At its simplest, QC is inspecting, testing or checking something (service or product) to make sure it's OK.
The intent is to identify anything that isn't OK, and either fix it or eliminate it, to make sure it conforms to the specifications, and has/does/functions as required.
QC is typically done at the end of the line, before it 'goes out the door'.
If the something isn't OK, this is called 'nonconformity' or a nonconforming service/product.
The goal of QA is to improve development and test processes so that defects do not arise when the product is being developed.
The goal of QC is to identify defects after a product is developed and before it's released.
Quality Assurance is Prevention of quality problems through planned and systematic activities including documentation.
Whereas QC represents The activities or techniques used to achieve and maintain the product quality, process and service.
It is important to establish a good quality management system and then carry out assessment of its adequacy &conformance audit of the operation system & the review of the system itself.
In QC Finding & eliminating sources of quality problems through tools & equipment so that customer's requirements are continually met For people not from this field the following example may help understand the difference between QA & QC : Think of QC as something like doing periodic checks to see that a horse is still in its stable, whereas QA would aim to make sure that the stable doors and gate locks work properly and that all the stable hands are trained and aware of the need to close and bolt doors properly

Quality Assurance: is to make sure standards are followed in an organization to esnure quality is achieved.
Quality Control: It is the control points ( inspection) that is made to the life process ( production) to ensure product conforms to requirements.
Note: QC is designed within QA.

QA is managment tool (system and specificatons)

QC is a production tool ( tests and inspection)

QC is validation; it answers the question: Have we done the right thing? Involves actual tests on product/material QA is verification; it answers the question: are we doing things right? It involves SOPs and planned arrangements and adherence to them.

Simply.

QC is inspecting, testing or checking service or product to make sure it's OK. 

QA is to improve development and test processes to ensure quality of a service or product.  

Any product which is produce as per their own recommended standard (such as raw materials, packaging materials, process parameters and finished product).
those standard ensure by QC And QA ensuring all kind of QC activities are doing wrong or right, just like verification and validation their own recommended standard.

QA is a set of procedures and system based on specific standards that must be followed in the production phase to get the products or services within these standards. 

QC is a set of testing tools used during the execution to correct any deviation from the desired product specifications.

this the final 

QA is managment tool function (Through system and specificatons)

QC is a production tool function( Throughtests and inspection)