what kind of degree do you need to become either a pediatrician or a cardiologist

Pediatrics & Cardiology r both specialties of medicine. This is what u would need to do to become either of these in the US
Both Pediatrics & Cardiology: Graduate medical school (4 years), Pass USMLE step 1(usually after the first 2 years of med school) & 2 (after the second 2 years of med school) Depending on ur grades in school, & ur USMLE scores u can 'match' for a specialty like cardio or pediatrics.

Pediatrics: Get accepted into Pediatrics residency program & complete a 2-3 year residency. If u want to be a pediatric specialist like a pediatric oncologist or something, u will need to do a fellowship program which will take a few more years on top of that.

Cardiology: This can be done in 2 ways. One-get accepted to internal medicine residency program(4 years), & do a fellowship in cardiology (3 years), or get into a cardiology residency program but the cardiology residency programs r HIGHLY selective & take about 5 years. It would be a lot easier to do internal medicine first & then try to get a fellowship in cardiology.

There r 6 year medical programs out there for people who do not have a degree or the admission requirments for med school yet, & 4 year programs for people who have at least a bachelors degree & the course requirements needed for admission.

Google is ur friend when it comes to these things there is a plethora of information out there.

To become a pediatrician or a cardiologist, you need to complete medical school.
Before getting into medical school, you need to have an undergraduate degree (4 yr degree).
After completing the 4 years of medical school, some docs complete fellowships.
We are talking about 8-10 years of college education. You may want to google ''medical schools''; there are far too many for me to list.