The words "last" and "past" both refer to a point in time or events that have already taken place. However, there are specific contexts where one is preferred over the other.
"Last" refers to the most recent occurrence of a specific event or period in time. For example, "last week" refers to the previous week
On the other hand, "past" typically refers to a longer and more general period of time, often relating to events that occurred before the present. For example, "past years" indicates a more broad timespan, not limited to a specific recent occurrence but rather encompasses a range of years in the past.
In summary, both "last" and "past" indicate events that occurred in the past, but "last" is more specific and recent, while "past" refers to a broader and more general time frame.