CONDTIONALS

The first conditional describes a particular situation, whereas the zero conditional describes what happens in general.

For example (zero conditional): if you sit in the sun, you get burned (here I'm talking about every time a person sits in the sun - the burning is a natural consequence of the sitting)

But (first conditional): if you sit in the sun, you'll get burned (here I'm talking about what will happen today, another day might be different)

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)