D will soon be outgrowing his 12-month clothing. As I'm looking at larger clothing, I'm seeing that there is usually a split - baby sizes are 0-24 months, and Boy sizes are 2T-whatever. H&M splits it 0-24 months and 1 1/2-10 years. Is there a difference between, like 24m and 2T clothing? Or 18m and 1 1/2y? I think the H&M split is specific to H&M, so if you can't answer that, cool. But with the 24m and 2T...? Is there any difference in size? Who knew buy kids' clothing would be so complicated.???