They are vague terms used in different ways in different contexts. Infant is generally on the younger end closer to birth and baby stretched out up to multiple years by some usage.

Newborn > infant > toddler with the option to call them a baby during all three. A child around a year old might be called an infant, baby, or even toddler.

Then don't use baby again until they are in a relationship :P

The definition I've heard the most is: newborn (0-3 mo.), infant (3-12ish mo, toddler (from the time they start walking to between about 2-3 years). Technically, any of them could be considered a baby.

"Toddler" describes the action of toddling, or walking in an uncoordinated way.

Baby isn’t a medical term for treatment purposes.

Baby can be older than an infant but also includes infancy.

Infants and babies are the same. Some people will continue calling their child a baby long after it is no longer a baby though. I have never seen someone continue to call their child an infant. So of the two, infant is more precise. A baby or infant will progress to become a toddler.

I think a child up until about 18mos is a baby. A new born is an infant.

i don’t know the specifics, but i feel they’re just synonyms and they share the same age range they’d represent. in terms of subgroup, id say infant is a subgroup of child based on what i hear and say. Like i wouldn’t say i have an infant baby id just say baby. Or i don’t have a baby child, i have an infant child. 🤷‍♂️

There's not a specific difference in most cases. But generally infant can be used outside of humans whereas baby is specifically a human child. And in some professional and scientific jargon infant is used to describe a specific phase of life.