Standard Webex meeting
Each time you schedule a standard Webex meeting, Webex creates a unique meeting link. Once scheduled, standard Webex meetings can be joined at the scheduled time by anyone with the meeting link, even if the host is late or doesn't join. Once the scheduled Webex meeting has passed, the link can't be used again.
Personal Room Meeting meeting
Your personal Webex room, on the other hand, has a single permanent link unique to you. The advantage is that you don't need to schedule a Webex meeting – you can send the link to people at any time, and ask them to join. Your Personal Room link will never change, unless you choose to change it in your preferences.