Magento Commerce is a premium eCommerce platform, while Magento Open Source is the free version.
The basic functionalities and structure are similar for both. However, Magento Commerce provides additional benefits and features, such as:
Marketing and merchandising tools
Targeted promotions
Customer segmentation
Cloud deployment option
In turn, SMBs often start with Magento Open Source, while larger enterprises with more complex requirements and the need for dedicated support may opt for Magento Commerce.