For the purpose of accessing a series EventArgument....

What is the difference between the MatchingRow.<fieldname> and just the plain <fieldname>, as shown below in the screen snip?

I have never been able to visually see a 'difference' in what they produce. The technical documentation we have on this topic only references how it is used to compare two different series, but its not clear which 'should' be used when simply accessing the field value of the calling event/action.