It's not confirmed, but there's strong evidence The Seed of an Idea was the pilot episode. It was the only episode animated by Nelvana, and for that reason it honestly looks a lot higher quality. The close-up zooms were more detailed and the characters had more expression in their movements.
Then the voice acting was clearly less professional. Honestly, that just made it cuter. Elinor's voice actor showed more emotion in Elinor's Circus and Burrowing Owl Girl, so that good too, but The Seed of an Idea was where they sounded the most like kids in my opinion.
But most importantly, a pilot typically introduces the characters and shows what they're all about. The episode did exactly that. Elinor doesn't seem to show near as much personality in most of the other episodes, though The Town Picnic and Owl Girl come pretty close. Yes, she does get excited and stunned at some of the things she learns later on, but that episode literally had her dragging Ari around by his watch until ripping it off his arm, even ignoring Ms. Mole to study it. That's dedication.
She also acts a lot more like a rabbit too. Sure she can jump higher than her friends, but I'd love to see her jump around on all 4's again if she gets excited or needs to get somewhere fast.