The reason why the population of North Korea is smaller than that of South Korea is because of the difference in the natural environment, the difference in the birth policy, the difference in the level of medical care, etc.
1.
1, the difference in the natural environment
According to statistics, the DPRK's land area is only 1/3 of South Korea's, and its population is 1/4 of South Korea's. The natural conditions in the north are worse than those in the south, such as fewer plains, lower temperatures, and insufficient precipitation, so the upper limit of the number of people that the north can support is not very high since ancient times. And with the accelerated urbanization, environmental pollution in North Korea is getting worse.
2, differences in fertility policy
North Korea and South Korea also have a large difference in population policy. The DPRK government has long pursued a family planning policy, emphasizing birth control and even encouraging the "one-child" policy. South Korea, on the other hand, has implemented policies to encourage childbearing, introducing a series of incentives such as "free education for children for three years after giving birth".
3, the difference between the medical level
North Korea's medical facilities are relatively poor, the number of hospitals is very small, the lack of medical equipment and medicines, health care is in poor condition. On the other hand, South Korea has a high level of medical science and technology and a favorable medical environment.
South Korea's population is as follows:
South Korea is a mono-ethnic country, belonging to the yellow ethnicity East Asian type, which accounts for 96.25% of the country's total population.On June 6, 2022, the Ministry of Administration and Security of the Republic of Korea (MOAS) released statistics showing that as of the end of May 2022, the registered population of the household registers of the city of Seoul, South Korea was 9,496,887 million people. After falling below the 10 million population mark in 2016, it fell below 9.5 million again after six years, leaving South Korea without a 10 million-population city.
As of Dec. 31, 2022, South Korea's household registration population was slightly over 51.439 million, down 0.39 percent year-on-year; the country's total number of households was about 23.71 million. Of these, about 41% are single-person households, numbering more than 9,724,000; the two types of households, single-person and two-person households***, account for 65.2% of the total. South Korea's male and female populations fell to about 25.637 million and 25.802 million, respectively, with the 50- to 59-year-olds accounting for the largest share of the population at 16.7 percent, and the 65-and-over group accounting for 18 percent.
Reference: Baidu Encyclopedia - South Korea