How is this different from the first conditional?
This kind of conditional sentence is different from the first conditional because this is a lot more unlikely.
For example (second conditional): If I had enough money I would buy a house with twenty bedrooms and a swimming pool (I'm probably not going to have this much money, it's just a dream, not very real)
But (first conditional): If I have enough money, I'll buy some new shoes (It's much more likely that I'll have enough money to buy some shoes)