Gmail is a free, advertising-supported email service offered as part of Google's G Suite, with 15GB of storage, color-coded inbox filters and unsend button.
Google Classroom is a learning management system (LMS) that aims to simplify creating, distributing, and grading assignments and engaging students in learning online or remotely.
Google Drive is a cloud storage and backup platform to access files, docs, photos & more, store them in a safe place, and collaborate with other people.