SQL Server - difference between instance name and instance id

By default, the instance name is used as the Instance ID. Instance ID is used to identify installation directories and registry keys for your instance of SQL Server. This is the case for default instances and named instances

(source: http://msdn.microsoft.com/en-us/library/ms143531(v=sql.120).aspx )

Install SQL 2008 r2 steps: http://blogs.msdn.com/b/petersad/archive/2009/12/17/sql-server-2008-r2-sysprep-step-by-step.aspx

I am not even a beginner but it's all in the references provided to you Jerry Dodge.

INSTANCE NAME = Is attached to a SERVER NAME just like the way it's stated. When you try to connect to an SQL Database you need the server to be able to get in. It's all about the networking and properties of your Physical or Virtual machine hosting your DATABASE.

INSTANCE ID = Is attached to SQL Instance Name. Once you provided the instance name which is the PATH to your SERVER NAME then you need the INSTANCE ID to be able to get into your programs and DATABASE path and all other software licensing requirements to run.

One is Physical or Virtual Computer and Network and the other is physical or logical path to the database storage.