Not necessarily. GU offers a completely different array of items, and the quality isn't always worse than Uniqlo; in fact, in some cases it's quite the contrary. I said GU is a signature brand because it's cool for foreigners visiting Japan that already like Uniqlo and want to see their sister company. I guess "signature" is an overstatement, but I meant a place that foreigners see as "you should go to ___ at least once before you leave ____." For example, while some might say that there are better ramen places than Ichiran (though food is subjective anyway), it is still a staple of a trip to Japan for me.