They have the same meaning. The only difference is who you are talking to. The word 'grown-up' is mainly used when adults are talking to children, or when.
“People who are merely adults, who haven't really grown up, assess risk in terms of the chances of getting caught engaging in risky behavior,”.
You can cobble together a solid 12 minutes of unconquerable joy a day staying home with a toddler. It's just the other 14 or 15 hours that strip.
Grown-up definition: A grown-up is an adult; used by or to children. | Meaning, pronunciation, translations and examples.
I have seen in many american tv series that the word grown-up is translated as adult in spanish. I guess adult and grown-up are synonimous.