Latest usually means the most recent up to now. Use it when something may be updated again later. For example: This is the latest version of the app. A newer one could still appear tomorrow.
Last often means final, or the one before now. It can refer to order, time, or sequence. For example: She was the last person to arrive. Here, it means no one came after her.
Last also appears in time expressions. In I saw him last night, it means the previous night, not the final night of all time.
- Use latest for the newest version, update, or news.
- Use last for the final item in a series.
- Use last for the previous time period, such as last week or last year.
A helpful contrast is this: the latest report means the newest report, while the last report can mean the final report or the previous report, depending on context.