1. She sent Ben a letter.

2. She sent Ben a postcard.
(Does #2 mean #1?)

3. Pretend you have been a frozen man for 20 years. You woke up just now. What are your plans for the future? I want to take exercise first. I plan to deliver a speech at a conference. I hope to see my girl friend.
(Is this passage grammatical? Would you check the errors? Thank you.)

A postcard is an open-faced correspondence, while a letter can be much longer and is typically enclosed in an envelope, so #2 does not mean #1.

Delete "take" in first sentence. It would be more specific to indicate the topic of your speech and the type of conference. By seeing your girl friend, does this mean attempting to re-establishing the relationship again? Although you have essentially remained static over two decades, her life has probably changed dramatically. Think about it.

#1 and #2 are different.

Letters are written on pieces of paper and then put in envelopes for mailing.
http://www.google.com/search?q=letter+and+envelope&es_sm=119&tbm=isch&tbo=u&source=univ&sa=X&ei=wUgBVLKIG-30iwLnyICwDg&ved=0CC8QsAQ&biw=1440&bih=707

Postcards are heavier paper, cut small, and mailed without the need for an envelope.
http://www.google.com/search?q=postcards&es_sm=119&source=lnms&tbm=isch&sa=X&ei=9EgBVKyVKcm7ogTiaw&ved=0CAgQ_AUoAQ&biw=1440&bih=707

I'd make a few minor changes in #3.
Pretend you have been frozen for 20 years. Now that you have awakened, what are your plans for the future? ...

1. In sentence #2, "She sent Ben a postcard," it means that the person mentioned in the sentence sent a postcard to Ben. The verb "sent" indicates that the person sent a message or communication to Ben, specifically in the form of a postcard. Both sentence #1 and #2 have the same basic meaning; they both involve a person sending something (in this case, a letter or a postcard) to Ben.

2. The passage you provided has a few grammatical errors. Here's the corrected version:

"Pretend you have been frozen for 20 years. You just woke up. What are your plans for the future? First, I want to exercise. I plan to deliver a speech at a conference. I hope to see my girlfriend."

In this corrected version, the main changes are:

- The phrase "you have been a frozen man" is changed to "you have been frozen" to make it more concise and gender-neutral.
- The phrase "just now" is added to clarify when the person woke up.
- The sentence about taking exercise is rephrased to "First, I want to exercise" for better clarity.
- The sentences about delivering a speech and seeing the girlfriend are rearranged for smoother flow.

Overall, these changes help improve the grammatical correctness and coherence of the passage.