There are two major categories of BPOs, the Drive By BPO and the Internal BPO. The name "Drive By" implies the extent of this BPO, but the task and form requirements can vary for this BPO type. Of course, in general the drive by BPO will not require the broker to get out of their vehicle nor go into the home. However, check the link out to see how this varies significantly by company and situation.
The Internal BPO can also vary in tasks and form requirements. It is definitely more involved, and there are usually more photos required. This BPO can require contact with a homeowner in foreclosure, or with a tenant who isn't aware of the situation. Care should be taken to know the situation and hopefully have an introduction before arrival.
For more detail on the duties of the two types of BPO, use these links: