Klaviyo and SendinBlue are two popular marketing automation tools. The primary difference between them is the focus of the services and the features that are available for each. Klaviyo focuses on email marketing, whereas SendinBlue focuses on both email marketing and SMS marketing. When it comes to features, Klaviyo is stronger in email and marketing automation, while SendinBlue is stronger in SMS, personalization, and integrations. Additionally, SendinBlue offers cheaper starter plans than Klaviyo, making it a great option for those just getting started with email marketing.