Speech - could be a proposal/request, a thank you speech on graduation day. This formats requires more first person POV and active voice.
Report - types of reports include: incident report, complaint report, event report, even police reports.
Article - this is to document an activity or event that you could have gone for, it is more factual and requires precision and structure
Formal Letter/Email - this can come in the form of a proposal / request / recommendation.
examples include requesting for an internship, a scholarship application, a vendor to fund an event, a town council letter, etc
Informal Email - usually to a family member or friend
Before you write,
Purpose: What is your objective?
Audience: Who is it addressed to?
Context: What is the situation or what are the circumstances surrounding this letter/speech?
Tone: Knowing the objective and audience will help you create an appropriate sounding letter that is not rude, informal or weirdly more formal than needed!