Tone is based on vocabulary and other parts of diction (grammar, syntax, concrete vs abstract, formal vs informal). Tone conveys the speaker's/writer's, we'll say speaker's, attitude toward and emotion about the topic being addressed. Mood is a very different thing. Mood is the feeling within the text itself. Mood is based on setting, people/characters, we'll say people, and descriptions. Mood is the feeling the listener/reader, we'll say listener, gets from within the text itself.
In some case the tone and mood may be very different while in some, they may be very like each other. For example, if a speaker were giving a Halloween speech intended to fit in with the spirit of Halloween and scare listeners, it is possible the speaker's tone might be bright and happy even though the mood of the scary ghost story might be dark and frightening. Conversely, a speaker might feel sympathetic about the subject, like at a speech explaining the need for a new children's hospital, and the mood sympathetic and sentimental.
Ronald Reagan's speech about the Challenger tragedy is of the latter (second) kind: his tone is sorrowful, sympathetic, and supportive while the mood is also sorrowful, sympathetic, and supportive. Since both speaker's tone and text mood are alike (they match), it may seem harder to tell them apart. Let's analyze them.
Vocabulary: the words are simple and direct, no sophisticated word.
Syntax: mostly simple sentences with some compounds and a few adverbial clauses or phrases:
- Today is a day for mourning and remembering.
- I know it's hard to understand, but sometimes painful things like this happen.
- Your loved ones were daring and brave, and they had that special grace, that special spirit that says, "Give me a challenge, and I'll meet it with joy."
Grammar: perfective tense/aspect, alternating between past perfective, "I'd [I had] planned to speak to you ...," and present perfective, "events of earlier today have led me to change"; simple present and past tense, "Today is a day for mourning and remembering. Nancy and I are pained to the core ..."; conclusion is future tense: "We will never forget them, ...."
Abstract/Concrete: mostly concrete words with some abstract. Concrete: planned, speak, tonight, report, etc. Abstract: mourned, pained, courage.
Formalism/Informalism: formal, though simple syntax; no colloquial speech, no slang, no idioms.
Therefore, we can say that Reagan's tone is serious, earnest, formal, yet sorrowful, sympathetic and supportive. When the content subject matter, the death of astronauts in an aerial accident, is combined with the vocabulary, grammar/syntax, and qualities of abstraction and formality, the analysis leads to the above understanding of his tone.
Setting: White House Oval Office, most important office in the country; national flags in the background.
Characters/Person(s): the persons are the President of the United States, astronauts' families and friends in the audience, school children of the US and all people of the US in the audience.
Descriptions: weighty and important events and circumstances; moral character; abstract notions of space pioneering; metaphor of heroic Drake; tragedy; etc.
We may say the mood within the text is formal, serious, sorrowful, and supportive and matches the speaker tone. Thus it can be seen that, while very different components of textual construction, tone and mood in this case match and complement each other.