What are the differences between mood and tense?

Tense is connected with the time of the verb's action, though the relationship is not always a simple one.

English is inflected for only two tenses, present and past.

Future events are expressed using the modal auxiliary will and such constructions are often called the "future tense."

Many grammars also use the Word "tense" to refer to constructions expressing progressive and/or perfect aspect.

Mood is more a matter of attitude.

The default mood in English is the indicative.

The subjunctive mood in English is used for hypothetical actions. Except for the verb "be," it can be distinguished only in the third person present singular, where subjunctives (e.g., "I asked that he leave the room") use the base form (e.g. "leave" in place of "leaves"). The base form be is used for all present subjunctive forms of that verb, and "be" has a past singular subjunctive, using "were" in place of "was" (e.g., "If I were a rich man").

The imperative mood in English is used for requests and commands and also uses the base form of the verb. Imperative sentences in English may omit the surface subject.

Some other languages have other distinctions in mood.