They mean exactly the same thing: a doctor who specialises in treating infants, children and adolescents. The only difference is spelling by region — paediatrician in British English, pediatrician in American English. If you are writing for UK readers, keep the extra a.
The core difference
Same word, same doctor, different regional spelling.
- pediatrician — American spelling: We took the baby to the pediatrician for her first checkup.
- paediatrician — British spelling of the same word: The paediatrician checked the toddler's growth chart.
How to tell them apart
There is no meaning difference to remember here, only a spelling one. British English generally keeps the ae in words built from Greek roots, while American English simplifies it to a plain e — the same pattern you see in paediatric versus pediatric more broadly.
A simple memory hook: British spelling keeps the fuller, older-looking form (paediatrician), while American spelling trims it down (pediatrician). Pick whichever matches the audience you are writing for and stay consistent throughout a document.
