You may notice that the invitation looks different when it arrives in your inbox. Changes to the emails it sends out for calendar events, tweaking them to look more modern and to surface important information quickly were announced by the company on Monday.
If an event is updated, the new design will show you the old info. If an event changes from 1PM to 2PM, you will see the 1PM start time crossed out below the new information to give you a better idea of what is happening. You can immediately know what to look for if you know what to look for.
The change should be rolled out by the end of the month. Those who manage their calendars through third-party tools like Fantastical or Outlook probably won't get much out of it (indeed, my email app doesn't even display these types of emails), for those using the Gmail web interface.