Relative pitched people will be able to easily match what the next pitch ought to be if you play the beginning of a song they know in a new key. Absolutely pitched people (in my experience, unless they've been trained) find this difficult.
Imagine if, someone showed you a two and you just saw in your head what 2 + 1, 2+2, 2+3, 2+4 were intuitively. This would give you a leg up in elementary math (And beyond). This is similar to what relative pitched people experience. An absolute pitched person often just sees the two and if they see a three, the relationship between the two has to be learned.