Rico, in American English your description was perfect. Although "Custom" and "Customized" can be used interchangeably as adjectives, most American English speakers would not use the adjective form of the word "customized". They would differentiate by using "custom" as an adjective and "customized" would be used in its verb form. Here are a few examples to further illustrate how I, as an American English speaker would differentiate the two words. "I make custom cabinets." - "custom" refers to the nature of the cabinets which can be made in any size, as opposed to stock cabinets, which are available in pre-defined sizes. (Applies to a broad audience - as Rico described) "I make customized cabinets." Although it has the same meaning as the first sentence and it would not be improper, for most Americans, the second sentence would sound wrong. "I have customized the cabinets to fit your kitchen." - "customized" as a verb (applies to a specific group, the homeowners, as Rico described).