Slack is considered (as of 2022) the more mature platform and offers dozens of useful integrations, while Teams' strength comes from its full integration with Microsoft Office and that its cost is included in some Office 365 plans. Slack and Teams are competing communications platforms for workgroups, both offer voice and video chat, natively and via app integrations. Slack also offers the option to use enterprise key management (EKM), single sign-on, and two-factor authentication to make data more secure. Slack encrypts data in transit and data at rest, but it doesn't offer end-to-end encryption.
Work moves faster when conversations do, too. Keep clients, vendors or partners in the loop by sharing a channel in Slack. Rather than trying to remember, easily find what you're looking for.
Projects end, teams change and Slack saves everything. Follow along with everything related to individual topics, projects or teams in their dedicated channels.