Are you a BRAND NAME DESIGNER LABEL homo sap? Didja know some store brand and name brands are made at the same plant?

It depends on the product.  Most food I do not taste a difference from brand to brand vs generac.  
With a few exceptions...I do not like JIF or Smucker peanut butter. 
In shoes I must have name brand tennis shoes. I am on my feet all day and generac shoes hurt my feet. 
Pretty much everything else is just decided by best deal and what I like at the time. 

That's not always true.  Some Private label products are made my bigger manufactures, but not all.  Not all private label product is as good as its name brand.  Then again, sometimes it's better.  If a company can get their Private label products made at a cheaper price, they will switch manufacturers.

Most clothing is made overseas (china and other smaller asian nations) by whoever will do it the cheapest.  Name brand means nothing.  A pair of Nike shoes may be made in China one day, then in Vietnam the next. They'll have the same Nike logo and may even look similar, but the "made in" country changed.

Stores are allowed to sell their product for whatever price they want (but no price gouging).  However, the price they pay for goods "at the back door" is usually not the price they sell them to customers for (mark-up).   Larger stores (chains) are able buy more product at a time from manufacturers as they have their own warehouses.  The more they buy at one time, the cheaper the price from the manufacturer (usually).  These savings can either be passed along to the customer (sales) or not.  It takes a LOT of money to operate one store (utilities, wages, product rent, garbage service, etc.).  A store must make enough money to pay the bills and turn a profit. This Is why many smaller stores have higher prices (of course they also have to compete or they go out of business).  ~Note: not all of a stores income comes directly from customer sales.~

Some stores may have lower prices, but they may not have great customer service.  Many people are willing to pay more to get good customer service.  Some stores (such as Walmart) have a reputation for not treating their employees fairly in order to make more profit.  There are people who will not shop at these stores simply because of that reason - even if the store prices are cheaper.

I look for quality in a product, NOT some designer labels (honestly, when you look at other people, do you look at the label on their clothes?).  I don't even care if some celebrity promoted it (I see that as a negative, not a positive).   Some "designer brand" product is inferior to its less expensive counterpart.