Diffen is a collection of differences and comparisons between any 2 things in the world.
What is the difference between LCD and Plasma TVs? Between DVD+R and DVD-R? How does living in New York compare with living in San Francisco? What is the difference between working with Microsoft and working with Philips? What is the difference between a Shia and a Sunni? A crocodile and an alligator?
Diffen is informational as well as recreational. So you can use Diffen to compare your two ex-girlfriends. Or you can find your own uses - no topic is taboo.