As the main consideration, the difference in nutrient needs between adults and infants exist because infants still haven't reach their maximum bone and muscle development. If being compared, the difference between the two would look like this:
Adults : - need about 100 calories of nutrient per kilogram
- Needs calcium and vitamin D to maintain bone structure
- Needs a lot more fiber than infant
Infants : - Need about 116 calories of nutrient per kilogram
- Needs calcium and vitamin D for Growth
- Need less fiber