Actually, if you do what anyone going on an interview should do for these types of doubts is show just a little prowess with Google. Search for "SSIS architecture" and be amazed. I would expect any and every candidate to be able to find the answers to these types of questions. It's just not that difficult. All you have to do is try.
Similar MS documentation is also available in Books Online. Lookup "SSIS" in BOL and then scroll down 4 lines and click on the word "Architecture".
I'd also expect a candidate to be proficient in being able to use Books Online.
--Jeff Moden
Change is inevitable... Change for the better is not.