To fix your confusion: Timers - generally considered one time. If you swipe away the notification the timer is finished. If you press the circular arrow button it will restart the timer. Pretty obvious. On the Lock Screen they are clearly labeled as "Done" and "Repeat"
Alarms - by default alarms are set with snooze on. Swiping away will snooze. There is a "ZzZ" and "X" button on the notification. On the Lock Screen they are clearly labeled as "Snooze" and "Stop". If the snooze function is disabled on an alarm the only option is to stop the alarm.
How is any of this unclear?