Although some people may think that clearing an app from Recent Apps menu will fully close it, they are unfortunately mistaken. There is a difference between clearing an app from Recent Apps menu and clicking Force Stop on it.
Clearing an app from Recent Apps menu may not fully close the app specifically the apps that use services such as Music Player, Whatsapp, Facebook, etc. When you clear Music Player for example, the music won't stop because the app uses a service running in the background, BUT if you force stop it from mobile settings, the music will stop hence the service is terminated.
So if you want to clear some memory to increase your RAM, you should force stop the apps that use services.
In conclusion, clearing an app from Recent Apps menu will only kill the activity lifecycle of the app but not the services that are run by that app.