My 4 year old son has completely outgrown all "T" sizes... 5Ts are just way too small. I've been buying him boys 4-6, depending on the item. Some 4s are still pretty big. Some are too tight. I would disagree that 5T and 5 are the same. I don't think the T sizes are the same as the boy sizes at all! At least not from the stores we typically shop in. If I were you, I'd go straight to boys size 6. Things might be a bit big, but at least they won't be too small.