Spot the differences ... this year's Booker judges with their favourites so far. Photograph: Stephen Kellly/PA

Every year, towards the end of longlisting for the Guardian First Book Award, I wait anxiously to find out which titles the Booker judges have chosen for their own longlist. You can usually predict which years are going to feature first books - there's a bizarre tendency (doubtless some pop economist is even now devising some theory of randomness to account for it) for all the "big hitters" to strike in the same year, leaving others wide open to newcomers. This was clearly shaping up to be one of those years

The issue isn't whether our tastes are going to be different, but whether publishers may have decided not to submit a particular novel at all (they're only allowed to send us three titles from a range of fiction, non-fiction and, in some cases, poetry too).

Of the four first novels up for this year's Booker, three are eligible for the Guardian prize (Peter Ho Davies has already published a short story collection). I was lucky: all three were in. Yet only one of them - Catherine O'Flynn's What Was Lost - appears on both lists. Why should this be?

Well, for a start the Guardian prize has no nationality bar - so we were able longlist Joshua Ferris's Then We Came to the End, whereas the Booker judges were not. (In the year that Jonathan Safran Foer won the our award with his wonderful novel Everything is Illuminated, a Booker judge sidled up and whispered enviously that it was probably the novel of the year).

Then there is the fact that short story collections are eligible for the Guardian prize, where they are not for any other fiction award not specifically devoted to the genre (which accounts for the bizarre fact that Alice Munro, arguably the greatest living fiction writer, has never won an international literary prize.)

But even accounting for these structural differences, the fact remains that two of the Booker longlistees don't appear on our list and one of ours - Tahmima Anam's A Golden Age - didn't make it on to theirs. (More starkly, we didn't longlist Stef Penney's The Tenderness of Wolves, which went on to win the Costa - formerly the Whitbread - this year.)

There are lots of other minor reasons for this difference, but beneath it all is the curious fact that over the years prizes develop their own personalities. The Whitbread is declaredly populist; the Booker tends to favour the thematically substantial, structurally sturdy, realist novel. Which leaves a gap for for us to sniff out the edgy, the playful, the unexpected, those pesky books that occupy the spaces between genres. It isn't the only place to be, but I can't think of a better one.