These days (1999) I distinguish between Modeling and Designing.  I say
	* "Modeling" is describing something you know. A good model makes correct assertions.
	* "Designing" is manipulating space for things you don't know. A good design e.g., lets you change things easily (there are many dimensions of 'goodness').
You take a drawing of the Model into the room full of business and database and other experts.  They critique it to see whether it contains any FalseAssertionsAndUnattractiveRestrictions regarding their business.  

--AlistairCockburn
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"Designing" for me is manipulating space for things you know for sure (i.e. you have running automated tests for). --KentBeck

''I love you - you do all designy things the reverse from me! -- Alistair (in a cheery mood on a sunny day.)''
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Just as a good design lets you change things easily, so does a good modeling language.  From ''InformationModelingAndRelationalDatabases'' by TerryHalpin, the following criteria provide a basis for evaluating conceptual modeling languages:
* Expressibility
* Clarity
* Simplicity and orthogonality
* Semantic stability
* Semantic relevance
* Validation mechanisms
* Abstraction mechanisms
* Formal foundation
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A design is a model without any implementation-specific or technology-specific details. A model is a design with those details.

Programmers are prone to seeing a spectrum of detail between designs and models, but this is false. There is a very sharp distinction between the two determined by the fact that users of a system only ever see its design whereas implementors are most interested in the model details. The ExplicitUserModel of a system is its design.

'''''Hmm.''' An ''architecture'' is a description (with visuals, perhaps) of a system containing modeling information, but lacking implementation or (sometimes) technology-specific details. A ''design'' is one solution to an architecture that fits technology to the system. The ''code'' is one particular implementation of the design that expresses a particular technology with specific details. This is the normal descent of granularity in designing. Eh?''
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