Google Meet is a video calling service which allows you to virtually connect face-to-face. It is similar to Zoom, FaceTime, and Microsoft Teams. Google Meet and Google Chat (formerly known as Google Hangouts) are often used in both personal and professional settings.
Google Chat (formerly part of "Google Hangouts") is a messaging app. You can use Chat to talk to people directly or in small group messages; collaborate in large, named groups called Spaces; send and share files from Google Docs, Slides, and Sheets; and set up tasks and meetings. Watch the Google chat course on YouTube to learn more about Google Chat's many features.
Google Voice: Google Voice gives you a phone number for calling, text messaging, and voicemail. It works on smartphones and computers, and syncs across your devices so you can use the app in the office, at home, or on the go.