Snov.io is a lead generation and automated outreach platform, while Mailshake is a sales engagement platform. Snov.io allows users to find leads and their contact information, as well as providing outreach campaigns and data tracking. Mailshake helps users with creating personalized emails and automating email campaigns. Mailshake does not provide the same lead generation capabilities as Snov.io, and it does not provide contact data. Additionally, Snov.io provides more in-depth data tracking and reporting, allowing users to track how many leads have been reached and what their responses were.