Load testing and stress testing are determined to test the stability of the developed application. most of test engineers are thinking both are same, but both testings are differ from each other.
Load testing is nothing but loading the full volume of capacity and testing whether the application is misbehaving (defects) as halting/crashing. Performance testing is similar but concern about only response time.
Stress testing is nothing but ensure the application is behaving normally on abnormal conditions like opening multiple tasks on the same application than specification needs and not on load.
You will get clear picture on example, let us take mobile application. Populate full load (fill all the phone book entries, SIM card entries, memory card, inbox) and do testing like searching for a contact under fully filled 1000 contact entries or with full load of memory card try to find for some files or try to send/receive large SMS frequently to test transfer of large packets. this kind of testing is called as Load testing. in this case, if u talk about only time response measure is said to be performance testing.
In the case of Stress testing, while on call send SMS frequently + receive another incoming calls + bluetooth is on active + Set the reminder to alram on the same occasion. this kind of abnormal senatio's of testing is said to be stress testing. making the application to handle the abnormal scenarios.
Hope you got clear picture. please let me know if you need any more clarification.
There is a lot of disagreement, even within the testing community, about these terms. But in general, performance testing refers to testing efforts that are focused on measuring some aspect of performance of a system. This is in contrast to functional testing, which concentrates on determining if a system operates correctly. As you get more specific, load testing is most often used to describe testing under realistic conditions to measure performance under the expected load. Stress testing tests a system under abnormal conditions - usually to determine how it will fail.
-> Performance parameters and scenarios identified for peformance testing after discussion with client
-> benchmark measures for the identified parameters received from the client
-> Performance testing done against these measures
Stress teting -> Well explained by Ganesh and Chris.
Load Testing -> The load need not necessarily be full volume at the initial test itself. While executing load testing, a pre determined load should be added to previous load with which the test were conducted and analyse the results. The load also need not necessarily be different loads and You can do load testing maybe with just one scenario for e.g. - increasing just no. of users for a specific scenario and see how the system reacts (e.g scenario can be "Member registration update" and see how the system reacts for 100 users, 1000 users etc..)
Ganesh : I would rather put it in a little different way.. You start with some pre-defined load and step by step you increase the load to reach to the full volume documenting and analysing the test results at each stage.
A short reply on ur topic hope you find it useful, Load testing & Stress testing both are part of Performance Testing.U can Do performance testing using load runner.Load testing is the one in which tester gives a Pre-defined load to the application and in stress testing we give More load than a Pre-defined One with less hardware resources.A very common example is a website having a capacity 1000's of user can click simultaneously.In stress testing we create a environment in which more than 1000 users clicks to it at a time and check whether application crashes or behaves abnormally.