In a mesh network, wireless nodes are connected with redundant interconnections. This helps to improve the reliability of the network, because if one node fails there are still other paths to get a message through the network.
In a routing mesh network, devices called routers are used to relay messages using a path determined by a networking algorithm. In a flood mesh network, messages are broadcast out by every non-sleepy node that receives the message.
In a star network, all end nodes are connected to one common central node, so all network communications pass through the central node. This creates a potential point of failure if the central node fails.