I've seen brown bear three times. Once on my first drive up to Alaska there was a sow on the road. I was driving a Toyota and she seemed to me to be almost the same size as the car. That's prob'ly an exaggeration. The other time on a hiking trip our party startled a young lone bear ahead of us, he took off up a thickly brushed hill at a speed none of us could have matched even unobstructed. The other time we observed a sow with cubs eating berries way down slope ahead of us, so we took a two hour break to let them put some more distance between us.

There used to be controversy as to whether grizzlies were the same species as brown bears and the consensus seems to be that they are, the 'hump' that supposedly characterizes the griz is a trait of some of the larger browns.

The current advice upon 'close encounter' with bears in the wild is that with a brown bear you play dead, with a black bear you are obliged to fight, because while Alaska brown bears have been known to kill people in the course of mauling, black bears have been known to eat people. This is by far the exception, the core problem with bears in the wild, similar to people in fact, is that they are unpredictable. A bear may have cubs nearby, a mate, might be in a bad mood, or protecting a food source.

The brown bear Oreo at the Anchorage zoo was obtained as a cub, they placed him in a with a polar bear cub named Apoon, and the zoo sold videos of them playing with each other, very cute. As they got older, one of them became much more aggressive toward the other (I forget which) and they were separated.

More advice on traveling in bear country:
When you are going into bear country, your best tactic is to let the bears know you are coming. Experienced hikers wear little bells. You should also carry deterrent pepper spray.
You should also be familiar with bear sign. Bear scat is found in large mounds containing little bells and smelling of pepper.