Performance Testing and Load Testing are different, But, both looks similar because the measurements used in analysis are same for both.
Performance Testing is done to understand the basestate of the application. It includes response time, Requests per second, etc
Where as Load Testing is done to find out the scalability of the system. For example, finding out the maximum number of users supported by the system with certain specifications. Here also, we need to measure the response time, Requests per second, throughput, etc.
In stress testing, we measure the recoverability of the system. For example, how the system recovers when we shutdown the DB while transaction is going on.
Or in another way, Load Testing comes under positive tests and stress testing comes under negative tests. And performance tests measures the basestate or performance of the system.
