Queues and flows are related but different options within LeadDesk. Both relate to how you handle inbound calls and messages.
Fundamentally, queues receive calls or messages and present them to your agents in order.
LeadDesk does offer more control than that though. As well as greetings and periodic announcements, you can define opening times, required agent skills, service level targets and thresholds for creating automatic callbacks.
Flows are a way of handling an incoming call or message before presenting it to an agent or adding it to a queue.
A simple call flow might play a greeting, set the language for queue messages, and then send the call to a queue. More advanced flows let you build a full IVR (Interactive Voice Response) system, providing menus, out of hours messages and prioritisation, before directing the call to one of several queues or straight to an agent, if necessary.
To learn more about the inbound options available to an admin, check out this section of the support page.
If you are an admin wanting to know more about creating flows, see this article in particular.