Hi AlexisS
Gosh they're covering a multitude of sins with that diagnosis. It sounds to me like "We think it's asthma but we're not very sure so we'll just call it something more vague in case we get it wrong."
Lots of babies get something called bronchiolitis - inflamation of the bronchioles in the lungs - that could be described as 'restrictive airway disease, just like asthma, bronchitis & other similar ailments.
If I were you I'd go back to the doctors who made the diagnosis & ask them exactly what they mean. I think you deserve a bit more explanation from them!
Good luck & I hope your wee girl gets better soon.
Lidia