NB vs. 0-3 month?

Re
I'm 33 weeks today and trying to finish up our hospital bag this week. We're due with our baby boy on December 19th, and I'd like to have a Christmas-y onesie for him to come home in but I'm not sure which size to buy. Are the outfits you're taking to the hospital/birthing center NB or 0-3 months? I can't tell much difference in them but curious to know what other mamas are doing! Thanks!