Identification of possible sarcopenia, which is a simple assessment of sarcopenia, has been proposed for the earlier detection of sarcopenia in primary care settings; however, there are no studies comparing the differences in characteristics of older adults with possible sarcopenia or sarcopenia. This study aimed to compare the characteristics of “possible sarcopenia” in real-world primary care and “sarcopenia” in research settings. A total of 2129 older adults were enrolled from the Korean Frailty and Aging Cohort Study. Possible sarcopenia and sarcopenia were defined using Asian Working Group for Sarcopenia 2019; the possible sarcopenia for real-world primary care was defined by a combination of case findings using low calf circumference or the SARC-F questionnaire and 5-times chair stand test, without considering the measurement of handgrip strength. The prevalence of possible sarcopenia was higher in women than in men; however, that of sarcopenia was higher in men than in women (all, p < 0.001). Older men and women with possible sarcopenia had a lower education level, longer time taken for the Timed Up and Go test, more severe mobility limitation, lower scores on the EuroQol-5 dimension and 12-item short-form survey for physical health, and more cognitive dysfunction than those with sarcopenia did (all, p < 0.05). In conclusion, the participants with possible sarcopenia differed from those with sarcopenia in some characteristics. Identifying differences in characteristics may be helpful to screening and earlier diagnosis of sarcopenia in real-world primary care, as well as in research, which can lay the foundations for personalized lifestyle intervention in diet and exercise.