Builder or Factory Pattern

Hi all,

I asked and touched on this subject before, but am still a little undecided as 
to the best course of action.

I have an application that will need to construct orders (invoices) with 
products.  The problem here is that the products are pretty diverse in their 
individual make up and why they are constructed.

For instance, some products include one or more "side" products which
must be 
chosen at design time.  At first glance, I thought Factory Pattern, but with the

complex "choices" that might be required in the building of the
product, I 
thought maybe Builder pattern would be more appropriate.

Thank you!

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Warm Regards,