Background: Dementia with Lewy Bodies (DLB) and Alzheimer's disease (AD) are two types of dementia with a relatively high incidence, and their clinical manifestations are easily confused. However, the cognitive impairment characteristics of the two diseases are different, and the results of cognitive assessment can help the diagnosis of the disease. Objective: To explore the different characteristics of Mini-mental State Examination (MMSE) and Montreal Cognitive Assessment Scale (MoCA) in DLB and AD patients, and to explore potential markers to distinguish AD and DLB. Methods: This study included 66 patients with DLB, 81 with AD, and 58 cognitively normal subjects. All of them completed MMSE, MoCA, and Clinical Dementia Rating (CDR). Results: Compared with NC, both DLB and AD participants demonstrated statistically lower scores in the total and subitem domains of MMSE and MoCA (p < 0.05). When CDR was less than 2, DLB patients had better performance than AD in two subtests including memory and orientation (p < 0.05), demonstrated worse performance in most subtest including executive function, writing, visuospatial abilities, and attention (p < 0.05). Nonetheless, no notable distinction in scores existed for the DLB and AD groups with a CDR score of 2 (p > 0.05). Conclusion: We observed distinct cognitive performances in subjects from both the DLB and AD groups across different stages of dementia. Our study confirms the high value of MMSE and MoCA in distinguishing patients with DLB and AD in the early stages of the disease, and they can improve the differential diagnosis of DLB and AD.