Enterprise WSDL:
a) The Enterprise WSDL is strongly typed.
b) The Enterprise WSDL is tied (bound) to a specific configuration of Salesforce
c) The Enterprise WSDL changes if modifications (e.g custom fields or custom objects) are made to an organization’s Salesforce configuration.
Partner WSDL:
a) The Partner WSDL is loosely typed.
b) The Partner WSDL can be used to reflect against/interrogate any configuration of Salesforce
c) The Partner WSDL is static, and hence does not change if modifications are made to an organization’s Salesforce configuration.