Consumer Staples are considered a more conservative and defensive sector. After all, no matter the economic conditions people still need "stuff" from soap to toothpaste. The earnings growth rate for these companies is more limited due to intensive competition as big box retailers have forced prices to remain lower. Big box retailers (Walmart and others) have also been able to dictate pricing terms to suppliers putting a squeeze on them. This has kept consumer prices lower no matter the pressure it puts on the small drug store around the corner.
A defensive sector like Consumer Staples will outperform when equity markets are more bearish and underperform when bullish. They will trend in the same manner overall but still with less beta or volatility since as indicated, even the worst of times, people will need stuff.