what's the different when using "plus" and the word "and"?

For example,
the choices to the problem were:
1. Cronkite was known for his honest presentation of the news PLUS his reassuring tone
2.Cronkite was known for his honest presentation of the news AND his reassuring tone

Thanks.

They both have about the same meaning.

But then the answer was choice 2.

What was the problem?

The word "plus" is not a conjunction except in informal speech:

http://dictionary.reference.com/browse/plus

The sentence requires a conjunction to join those two phrases.

When using "plus" and the word "and" in a sentence, they can have slightly different meanings.

In the example you provided:

1. "Cronkite was known for his honest presentation of the news PLUS his reassuring tone."

In this case, the word "plus" is used to indicate that two distinct qualities or attributes are being added or combined together to enhance the overall description of Cronkite. It implies that his honest presentation of the news and his reassuring tone are both important and contribute to his reputation.

2. "Cronkite was known for his honest presentation of the news AND his reassuring tone."

In this case, the word "and" is used as a conjunction, indicating that both qualities of Cronkite (his honest presentation of the news and his reassuring tone) are separate, but equally important. The use of "and" suggests that both qualities exist independently and are not necessarily related or dependent upon each other.

To determine the difference between using "plus" and the word "and," it is important to analyze the context in which they are used. In general, "plus" implies a combination or addition of qualities, while "and" suggests separate but equally significant elements.