停止 vs. 停住 usage/difference?
Both 停 and 止 contains the meaning of 'to stop'. 


"停止" is a compound word verb for 'to stop' 
"停住" = "to stop (successfully/ and keep it this way). It is made up of the verb '停' and it's result complement '住' (住 as a result complement denotes: 1. successfully; 2. in a continuous state)



  停止 is usually used as an intransitive verb or auxiliary verb


Example :

(intransitive verb): 操作停止 (operation stops); 任务停止 (mission stops)

(auxiliary verb): 停止攻擊 (stop attacking); 停止操作 (stop operating)


  "停住" can be use transitive or intransitive


Example :

(transitive verb): 他停住車子 (he stops the car)

(intransitive verb) 車子停住了 (the car stops)