Hadoop job -kill job_id and yarn application -kill application_id both commands is used to kill a job running on Hadoop.
If you are using MapReduce Version1(MR V1) and you want to kill a job running on Hadoop, then you can use the Hadoop job -kill job_id to kill a job and it will kill all jobs( both running and queued).
In MapReduce Version2(MR V2 or YARN) when you submit a MapReduce job, It process through an application master and hence the job called application. There could be multiple tasks running within an application. If you want to kill an application then you can use yarn application -kill application_id command to kill the application. It will kill all running and queued jobs under the application.
If you want to kill a task in YARN then you can use hadoop job -kill-task <task-id> to kill a particular task in YARN
This link will be useful to understand application and job in YARN.