Hello,
Paediatric junior doctor here training to be a paediatric consultant. I graduated from medical school 7 years ago but can give you a perspective on what paediatric medicine involves.
Paediatrics is broader than many other medical specialties. In adult medicine you might be a cardiologist or a gastroenterologist, in Paediatrics most doctors tend to look after the whole child with only a few subspecialising in the rarer conditions. This is great as it means you get loads of variety in your work and get to practice in a holistic way taking care of a child and their family.
The main areas within Paediatrics are neonatal medicine and neonatal intensive care (looking after babies born unwell and/or prematurely), general Paediatrics (children that are usually well but become unwell and need hospital care and those with long term conditions like diabetes, cystic fibrosis, and community paediatrics (children with disabilities or behavioural conditions, also children with additional social needs like adopted children or safeguarding concerns.
As a junior doctor after you qualify you rotate through all of these and you tend to pick parts of it you enjoy most and train more in these as you qualify as a consultant.
Studying medicine is long and hard regardless of which area you specialise in after you qualify. As a junior doctor life is different to most other graduates, you work a 48hr working week as standard, have to work nightshifts and weekends, you have to do more exams after you graduate (which you have to pay for and study for in your own time).
If you are considering applying for medicine then I'd strongly advise getting some work experience and not just with GPs or consultants but with junior doctors and medical students who can give you an accurate idea of what it takes to get to the end point.
I really love Paediatrics and think my job is great but generally think most teenagers applying to medicine have little idea of what they are signing themselves up for. Go in with your eyes open!