Skype Meetings App and Skype for Business Web App are browser-based meeting apps that you use to join Skype for Business meetings. You can't schedule a meeting from Skype for Business Web App, but you can join a meeting that was scheduled by using either Outlook or Skype for Business Web Scheduler.
Depending on how your organization is set up, you will use either Skype Meetings App or Skype for Business Web App.
To join a meeting by using Skype Meetings App or Skype for Business Web App, just select Join Skype Meeting in the email or calendar meeting request you received. If the computer you're using doesn't have Skype for Business installed, a browser window opens and you can join the meeting.
Comparison with other Skype for Business clients
Skype Meetings App and Skype for Business Web App provide HD video conferencing, IM in meetings, high-fidelity desktop, application, and presentation viewing, desktop sharing, whiteboard, lobby, and presenter access controls. In addition, Skype Meetings App and Skype for Business Web App now include PC-based audio and video. They don't offer any other Skype for Business features, such as presence or contact information. For more information, see Skype for Business Online Service Description and Client comparison tables for Skype for Business Server 2015.