In a bull market, the bulls are the dominant force, and shorting requires caution because the bulls can retaliate very quickly, so it's best to take profits when shorting.
In a bear market, the bears become the rulers of the market, and going long means seizing the opportunity to rebound, as the bears can push prices down at any time.
Remember! Don't always think about trying to catch the top or the bottom, as you might just become fuel for the market.