The main difference between Smartreach and QuickMail is their approach to email marketing. Smartreach focuses on personalization and provides tools to segment email lists and create targeted campaigns. On the other hand, QuickMail places more emphasis on automation and offers features to automate email campaigns and follow-ups. Smartreach also includes features for outreach and prospecting, while QuickMail is primarily designed for cold emailing. Ultimately, the best choice depends on the specific needs and goals of the user.