Trustpilot is a tool to collect reviews from customers. Those reviews are leveraged on-site to increase conversion rates or used to increase visibility with Google. Trustpilot automatically sends review invitation emails and reminders to make it easy for your customers to leave feedback.
Segment is a Customer Data Platform (CDP). They provide a service that simplifies collecting and using data from the users of your digital properties (websites, apps, etc). With Segment, you can collect, transform, send, and archive your first-party customer data.