Objectives: The clinical features of Alzheimer’s dementia and vascular dementia are very important for determining the treatment direction, understanding clinical symptoms, and predicting disease progress. This study compared cognitive functions according to dementia type in patients with Alzheimer’s dementia and vascular dementia. We examined the sub-areas of cognitive functions that can distinguish between the two diseases, the extent to which the two dementias can be differentiated by area, and how this can be used for intervention. Methods: The subjects were 55 patients with Alzheimer’s dementia and 15 patients with vascular dementia. The cognitive function of the two groups was compared using analysis of variance (ANOVA), and the accuracy of dementia classification was determined using discriminant analysis. Results: When cognitive functions were compared between the two groups, patients with vascular dementia had significantly higher scores in the word-delayed recognition domain, and there was no difference in the remaining cognitive functions. The accuracy of classifying the two groups based on word-delayed recognition domain was 65.7%. Conclusions: Word-delayed recognition was the only cognitive domain that showed discriminatory power between the two dementia groups. A communication technique using word-delayed recognition can be used as an intervention for patients with vascular dementia.