Can "ragazzi" and "bambini" be used interchangeably in some contexts?
I know "bambini" is 'babies' or 'young children' (or immature/naive) and the word has many other uses, but does "ragazzi" only mean 'children' and that's it or does it also have multiple meanings?
The two words are (mostly) not interchangeable. The meaning of the words change in different contexts.
Age: A ragazzo is maybe age 14-24 (possibly 29 or 30) "Young adult". A bambino is age 4 - 14 "Child". A bambino can begin a birth, but normally children between 0 - 4 are referred by by other words. Some times a bambino is in grammar school; while a ragazzo is in high school, college, and a few years beyond college. Sometimes the boundary between ragazzo and adult to being married, having children and your own apartment.
As you can guess often someone may be a ragazzo in one conversation and an adult in another.
Romantic: Boy friend (ragazzo) or Girl friend (ragazza) - any age from teen to one hundred.
Activity: Friends (any age adult) engaging is a fun activity, that may be associated with youth, may call each other ragazzi. For example 40 year old friends playing soccer at the company picnic. Or senior citizens playing bocce.
Referring to younger people: (be very careful can mean admiration or scorn). For example 60 a year old referring to 50 year old.
When in Roma, I walked past una farmacia that had a large advertisement in the window that read "Prodotti Mamma Bimbo".
Which I believe means "baby momma" products.
So I'm guessing that newborn could be bimbo, bimba, bimbi and maybe even bimbe in some cases.
Based also on this image, that I found online (not easy to search):
Bambino and bimbo are always fully interchangeable.
A newborn is called neonato / neonata for the first 4 weeks / 1 month.
Then, colloquially, he/she is already bambino or bambina. More specifically, the word lattante is used until the weaning has been completed.
As far as I know, "ragazzi" is used for older children, youngsters and young adults. I read an newspaper article about an 27 year old man who was described as "ragazzo".
Also, "mio/a ragazzo/a" is "my boy/girlfriend".
In Italian bambino is baby or child and ragazzo is boy or boyfriend. Baby is more like a toddler and child is a little older