1. Agents by Queue Tab
The Agents by Queue tab provides information about how well your queues are covered. Every queue that has at least one agent that’s Online or Away is shown. You can see how many agents are assigned to the queue and how many of them are online, away, or idle. This graph lets you see if you need to rearrange any agents to make sure your incoming work is covered.
Reference Article – https://help.salesforce.com/articleView?id=sf.omnichannel_supervisor_agents_tab.htm&type=5
The Agents by Queue tab provides information about how well your queues are covered. Every queue that has at least one agent that’s Online or Away is shown. You can see how many agents are assigned to the queue and how many of them are online, away, or idle. This graph lets you see if you need to rearrange any agents to make sure your incoming work is covered.
Reference Article – https://help.salesforce.com/articleView?id=sf.omnichannel_supervisor_agents_tab.htm&type=5
2. All Agents Tab
This shows only partial list of users and not all the users. So, it won’t match the count against Agents by Queue.
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