Lifespan is the maximum period of time a species lives. The human lifespan is measured in years. As of 2020, the documented human lifespan is 122 years (see also lifespan concept in psychological science).
Life expectancy is the average period of time a member of a population with certain characteristics lives. Human life expectancy, measured in years, varies by sex and environment. Human life expectancy varies by the age group. For example, life expectancy of people at birth will be different from a group of people who are alive at age 70.
United Nations data are reported by sex and country. Overall, there has been an increase in human life expectancy on a worldwide basis between 1950 (47.0 years) and 2020 (73.2 years; worldometers). I have rounded the numbers which were reported up to two decimal places.
Examples of recent life expectancy data for wealthy nations reveal marked differences compared to other nations.
Data from the United Nations -- see the full chart and details at worldometers.
Life expectancy of laboratory animals varies with the species and strains of the species. The life expectancy of rats and mice is measured in days.
Life expectancy data are also reported in life tables. Period life tables are available from the US Social Security program (Social Security Administration; SSA). These tables organize data by age group and sex. SSA also provides downloadable reports. The tables also give the probability of death for men and women. The tables are available based on historical data as well as estimates of the future (for examples, see ssa).
SSA has a life expectancy calculator based on gender and age (ssa calculator). The results provide an estimate, but they note that the estimate does not consider such relevant factors as health, lifestyle and family history.
Death rates are usually reported by sex, year or time period, and per 100,000 people in a population. According to US Social Security study 120 in the year 2000, people died at the rate of 867 per 100,000 but this varied by age group. Under age 65s died at 243 and over 65s at 5,261. The data were different for men and women. For those over age 65, 6458 men died compared to 4,530 women (https://www.ssa.gov/oact/NOTES/actstud.html). Note- I have rounded the numbers.