What is the difference between sequential and parallel testing?

In AppLoader, tests can be executed either sequentially or in parallel. Here is the difference between the two:

Sequential: rUsers will start sequentially, by scenario, across all Injectors assigned to run the test.
For example, assuming the test will run on two injectors and the delay is 1 rUser every 10 sec: Injector 1 starts rUser001, then Injector 2 starts rUser001 after 10 sec, then Injector 1 starts rUser002 after 20 sec, then Injector 2 starts rUser002 after 30 sec and so on...

Parallel: rUsers will start at the same time across all Injectors assigned to run the test.
For example, assuming the same test will run on two Injectors and the delay is 1 rUser every 10 sec: Injector 1 starts rUser001, at same time Injector 2 starts rUser001, then Injector 1 and Injector 2 will start rUser002 after 10 sec and so on...