Final answer:
Developing countries generally have more youthful populations due to higher birth and fertility rates. Low-income nations have higher total fertility rates and population growth rates compared to high-income nations.
Step-by-step explanation:
Developing countries generally have more youthful populations than industrial countries due to higher birth and fertility rates. This is because many low-income nations have a higher proportion of youth and young adults, while high-income nations have a larger share of elderly population. As per the World Development Indicators database, low-income nations had much higher total fertility rates and population growth rates compared to high-income nations.