WCF Service Base Address vs endpoint address

WCF Service Base Address vs endpoint address

What's the difference between the following two cases:
Configuration 1:
<service name="WcfService1.Service1"
behaviorConfiguration="MyServiceTypeBehaviors">
<host>
<baseAddresses>
<add baseAddress="net.tcp://127.0.0.1:808/" />
</baseAddresses>
</host>
<endpoint address="service"
binding="netTcpBinding"
bindingConfiguration="MainBinding"
bindingName="MainBinding"
name="DefaultEndpoint"
contract="WcfService1.IService1" />
<endpoint address="mex"
binding="mexTcpBinding"
contract="IMetadataExchange" />
</service>
Configuration 2:
<service name="WcfService1.Service1"
behaviorConfiguration="MyServiceTypeBehaviors">
<host>
<baseAddresses>
<add baseAddress="net.tcp://127.0.0.1:808/service" />
</baseAddresses>
</host>
<endpoint address="net.tcp://127.0.0.1:808/service"
binding="netTcpBinding"
bindingConfiguration="MainBinding"
bindingName="MainBinding"
name="DefaultEndpoint"
contract="WcfService1.IService1" />
<endpoint address="mex"
binding="mexTcpBinding"
contract="IMetadataExchange" />
</service>
What I understand is In either case base address + endpoint address
resolves to same absolute address
But why I get the error on Configuration 2 : "No end point is listening at
net.tcp://127.0.0.1:808/
but Configuration 1 runs the service without any errors!!!