Difference between OEM install and custom Ubuntu image

I'm looking into the best way to deploy a customized Ubuntu image and it looks like I have two options:

1. To make an "OEM install" version.


2. To make a custom Ubuntu image.

Could someone help me understand the difference between these two methods of customizing an Ubuntu install? It appears to me that both these methods allow for elaborate customization of the image while allowing the user to enter their own end-user details (time zone, username, password, etc...).

The OEM Install

• The OEM install allows machine by machine customization.


• It does not create an ISO image, but customizes a single machine.


• Customization is done at the stage of installation.

Advantages

1. Do not require a custom iso.



2. Each machines can have different customization.


3. Suitable for small number of customized machines, each with its own
   set of customization.


4. Also suitable for uncustomized machines where user gets to setup her
   own settings.

Disadvantages

1. If each machine needs to be customized the same way, they still have
   to be done individually at the time of install and thus, will take
   longer.


2. You will need some other tools to create an iso image.

Custom Ubuntu Image

• On the other hand custom Ubuntu Image allows making a single
  
  customized iso.




• Copy it in multiple CD/DVD/USB




• Deploy the same image in multiple machines quickly.

Advantages

1. Suitable for large volume deployment of identically customized
   machines.

Disadvantage

1. Requires an extra step of creating and testing a custom iso
   image. May not be worthwhile for one or two machines.