Define "flat" and "hierarchical"?

define "flat" and "hierarchical" in terms of software development
The use of components (and controls)provide a development environment which is "flat" in comparison to the deeply hierarchical environment of class namespaces which must be mastered in pure object oriented environments.How would you describe this in a much more lengther way with examples,
And the reasons if you aggree or disagree with either of there two, and why?
Thanks for the previous answers. I appreciate it very much.

I don't have time or space to write a paper on the subject. "Flat" and "hierarchical" models are about scope and visibility. The items/objects which are visible (or not) depend on the environment you're working in (programming language/database/etc.).

"Flat" offers some conveniences and assists re-usability, but can permit errors especially in environments that don't enforce type checking. "Hierarchical" supports re-usability within the silo of the hierarchy and makes re-usable items more apparent to the developer. Structuring a hierarchy requires more forethought to make the items visable in all the contexts one wishes to use them.

As for examples, C vs. C++ vs. C# would be one. QuickBasic (of long ago) vs. VB 2005 would be another.

I wouldn't agree or disagree with either, outright. I consider them different tools for different jobs. Persons of different skills may get a task done faster using different tools--the ones that fit their level of understanding and ability.