From the oracle documentation:
Local Naming
The local naming method stores connect descriptors, identified by
their net service name, in a configuration file on the client named
tnsnames.ora. This file is located in the ORACLE_HOME/network/admin
directory.
Directory Naming
The directory naming method stores connect identifiers in a
centralized, LDAP-compliant directory server.
Easy Connect Naming
The easy connect naming method enables clients to connect to an Oracle
database server by using only a TCP/IP connect string consisting of a
host name and optional port and service name:
CONNECT username/password@host[:port][/service_name]
For example:
CONNECT hr/hr@my-server:1521/mydb
The easy connect naming method requires no configuration.
External Naming
The external naming method stores net service names in a supported
non-Oracle naming service. These supported third-party services
include:
Network Information Service (NIS) External Naming
Distributed Computing Environment (DCE) Cell Directory Services (CDS)
This should make the distinction between the different naming methods very clear. How the EZ connect overloads the listener is not clear to me (is this from a rumormonger?). Basically this only converts a EZ connect alias to the common tns alias. However more advanced connection attributes like CLB/RLB or connection pooling cannot be specified with a EX connect string.
