Installed applications can be cleared or stopped in various ways. There is notable difference between clearing app from application list and forcing app to stop from settings menu.
Application can be cleared from the Recent Apps menu by swiping it to the right or left or clicking cross button at top of preview window. Application can be stopped from Settings -> App -> Running -> Force Stop. It is important to check that they send the same signal to the running process and whether they stop the services launched by the app.
Some users may think that clearing an application from Recent Apps list will fully close it, but it is not true. Clearing an app from Recent Apps menu may not fully close the application that typically uses background services. These background services periodically user internet and check for updates from server and display notifications to user. Its examples include Music Player, Whatsapp, Facebook, Twitter, Instagram etc.
When user clear Music Player, the music does not stop because the application uses a service running in the background, but user force stop it from settings, the music will stop hence the service is stopped. Also, application like Facebook or Whatsapp display notifications, even after cleared from recent apps list. They stop displaying notifications only after stopped from settings. So, if user has to clear some memory to increase your RAM, force stop should be performed to stop the service completely.
Recent apps basically are the applications has recently used by the user. It is different from Alt-Tab of desktop computer, where user explicitly switches through running apps. Application has still processes running, but its resources are generally using limited amount of RAM and would be automatically freed as soon as they are required for other processes. They do not consume battery, CPU or other system resources.