Apart from the intensity of the feeling, is there any other difference between "surprised" and "astonished"?

Question

EDITED

Surprise (verb)

• Cause (someone) to feel mild astonishment or shock.
• Capture, attack, or discover suddenly and unexpectedly. http://www.oxforddictionaries.com/definition/english/surprise

Astonhish (verb)

• Surprise or impress (someone) greatly http://www.oxforddictionaries.com/definition/english/astonish ("off-topic". To me, it is surprising that the same dictionary should use "surprise" to explain "astonish", and vice-versa.)

In the following passage, from an old issue of The English Teaching Journal, "surprised" and "astonished" are said to have a difference in meaning, other than the intensity of the feeling.

The university professor slipped his arm round the waist of the housemaid just as his wife entered the room. "Really, George", she exclaimed, "I'm surprised at you!" "To the contrary, my dear," he replied, "it is we who are surprised. You are astonished."

This was published about forty-five years ago, even though the anecdote seems to antedate it by over a century, as referenced by @Erik Kowal in his comment below. In addition, I've been told such use of "surprise" is outdated. All this said, here is my question: Is this use of "surprise" (catching somebody "red-handed") still current usage?

Answer 1

To surprise someone can also mean to catch them by surprise, usually in some surreptitious (and often improper) act.

The professor quips that his wife has surprised him and the housemaid in illicit canoodling.

ADDED:
Yes, the sense of catch in the course of a (usually) improper act is still current. Here are some recent uses from Google:

Police Calls: April 25-27 (another burglar surprised in the act)—Orange County Register, 4/28/2008

Authorities said the killer struck when the other men surprised him trying to steal an "ultralight plane." —KTEN-TV,6/14/2012

mornin'! found at last night that my cat food bowl thief (the food on my carport) is not in fact the raccoons, but is a big stray dog that i surprised in the act last night. now i gotta figure out what to do. fun stuff on the bayou... —Daily Kos, 'The Breakfast Club', 4/6/2014

Answer 2

Oxford Learners Dictionaries makes some distinction:
See Usage Note under astonish:

surprise to give somebody the feeling that you get when something happens that you do not expect or do not understand, or something that you do expect does not happen; to make somebody feel surprised: The outcome didn't surprise me at all.
…
astonish to surprise somebody very much: The news astonished everyone.

Interestingly astonish comes from the word for (hence, strike like) 'thunder.'