One accepts campaign contributions from those doing business with Cuba's criminal and murderous regime, and the other one doesn't.

... Cuba is a passionate point of contention in the fiery race between Rivera, a Republican, and Garcia, a Democrat. The two Cuban Americans -- who at different times each worked for the same powerful Cuban-exile group -- back the trade embargo and a ban on U.S. tourist travel, but are otherwise at odds on greater engagement with the island.

For evidence, look no further than their campaign contributions: Those who want more travel to Cuba are contributing to Garcia. Those in favor of keeping tougher sanctions against Cuba back Rivera.