Demands for whole blood (WB) and COVID-19 convalescent plasma (CCP) donations during the SARS-CoV-2 (COVID-19) pandemic presented unprecedented challenges for blood services throughout the world. This study aims to understand the motivating factors that drive WB and CCP donations in the context of the pandemic. This cross-sectional study is based on data extracted from surveys of the two volunteer donor cohorts. The findings reveal that when compared to CCP donors, WB donors were more likely to view donation as a form of social engagement (97.7% vs. 87.1%, p < 0.01), advantageous in the workplace (46.4% vs. 28.6%, p < 0.01), advantageous in their social network (58.6% vs. 47.0%, p = 0.01), and view their donation in the context of positive self-satisfaction (99% vs. 95.1%, p = 0.01). The average age of CCP donors was 7.1 years younger than those who donated WB (p < 0.01). Motivational factors were also analyzed by sex and religiosity. In conclusion, whereas both donor groups showed a high motivation to partake in these life-saving commitments, WB donors were more likely to be motivated by factors that, when better-understood and implemented in policies concerning plasma donations, may help to increase these donations.