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 Engl
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 couldn't 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:
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 isn't part of the question but it's related, I think...)