toddler sizing question

flamencogal

I'm getting ready to order some clothes for Scott and we went to the store and tried on 4T and boys size 4 shirts and I don't really see much difference.  Is there a difference?  I want him to be able to grow into them some.  This summer he's worn a 4T in shirts but is boys 4 a size up or not?  I'm confused.  And yes, I teared up a little when I realized that 4T was as big as the toddler sizes go...my boy is growing up!