tell the difference

The world should fear another four years of wondering if he can tell the difference.

In one post a man attempted to determine which group of Republicans showed up at a political forum: “Who were they, the far right-wing nut job part of the tea party, regular tea party, or the newly found conservatives, how do you tell the difference, and how many actually live in the precinct.”

"Admittedly I'm no expert but I couldn't tell the difference."

And I think you can tell the difference.

My husband swears by adding a pinch of baking soda, but I can’t tell the difference one way or the other.