Diono Olympia vs Diono Radian RXT

Hi Kate, Thank you for your enquiry. Firstly the Diono Olympia has a slightly wider seat shell compared to the Diono Radian RXT, but the main difference being the Diono Radian RXT has the adjustable reinforced head rest for complete side impact protection and the infant and toddler cushioned inserts for full body support. We hope this helps with your query