What is the difference between Total Event and Unique Event?

Basically,

Total Event( click/page view) = How many times were this event occurred.

Unique Event ( click/page view) = How many people or sessions triggered this event.

For Example:

John visited my website and click a button which is tracked by google analytics “5 times”.

Total Event = 5

Unique Event = 1

And then, Mary visited the website after John .This time, she clicked the same button “3 times”.

Total Event = 8

Unique Event = 2

Now you can see the difference between the Total Event and Unique Event. Both of them has their own statistical significance, but I think unique event is more useful for most of people.

FYI, Unique event can prevent Invalid clicks. Because no matter how many clicks triggered by one person(session). It was counted as one click in unique event.

Reference: About Event