What's the difference between Architectural Patterns and Architectural Styles?

Question

In Software Architecture - Foundations, Theory and Practice, I can find definitions for both. The problem is that I don't get what each one of them means in plain english:

Architectural Pattern.

An Architectural Pattern is a named collection of architectural design decisions that are applicable to a recurring design problem parameterized to account for different software development contexts in which that problem appears.

Architectural Style.

An Architectural Style is a named collection of architectural design decisions that (1) are applicable in a given development context, (2) constrain architectural design decisions that are specific to a particular system within that context, and (3) elicit beneficial qualities in each resulting system.

So, could anyone clarify in simple english what does each one mean and what are the differences between them?

Answer 1

For Architectural Patterns think specific ways to style your code as described by the GoF like; Adapter, Strategy, Builder, Mediator, etc

For Architectural Style think overall system; I.E., using MVC for presentation, DDD to model the business layer, WCF (if you're into .NET) for Interop, SOA for integration, etc.

Answer 2

Frankly, i have always considered both these terms to be synonymous! And layman (relatively speaking) literature definitely treats them as such. Refer MSDN or Wikipedia

However, your question intrigued me a bit so i did a bit more digging and frankly...i couldnt find much except for a reference to A Practical Guide to Enterprise Architecture (The Coad Series), from which i quote :-

An architectural style (Base et al. 1997) and an architectural pattern 
(Buschmann et al. 1996) are essentially synonymous. 

Based on some more googling, this is what i think might be one possible way to differentiate the two

• An architectural style is a conceptual way of how the system will be created / will work
• An architectural pattern describes a solution for implementing a style at the level of subsystems or modules and their relationships.

How an architectural pattern will differ from a Design pattern i.e Adapter, observer is basically by the level of Granularity at which they are applied (I know this isnt part of the question but its related, i think)