The guy at Delta has to tell you that and it is partly true. The external of the faucets are pretty much exactly alike. The main difference is the internal parts. Don't misunderstand, the internal parts are actually interchangeable for the most part. The main difference is for instance on a Delta 400 single handle kitchen faucet I buy from a box store will have a plastic or nylon ball where the one I purchase from Ihrie or Wilkinson will have a stainless or brass ball. Other faucets will have plastic vs ceramic cartridges. What I would recommend if you don't believe your local plumber is to go to a supplier and actually pick up a Delta faucet and feel it. Then go to the box store and do the same. I think you will feel the difference in the weight. Here is the real reason I recommend buying your faucet from me and I buy it from the supply house; if I buy it and install it I give you a no questions asked warranty for 2 years. If it drips or leaks or any other issue the supplier gives me a new one and I install it and you are happy. On the other hand, if you supply the faucet from a box store I can't do that. It just takes too much time on the phone and in the store for me to warranty it. I warranty the labor only in that case so if it leaks I charge you again because it cost just as much for me to install a faucet that leaks or drips as it does one that doesn't. I've even had customers want me to install a faucet they removed from an old house 5, 10 or 15 years ago and " It worked fine then." I always try my best to talk them out of that because the sales, o rings etc are too old and cracked and I've never had one not to leak. Good luck. More on reddit.com

Actually I think it's that companies like Moen, Delta, Kohler make faucets to the specifications dictated by Lowe's and Home Depot, which is inferior to the specs for faucets sold through plumbing supply houses. More on reddit.com

From This Old House: Aside from style and features, what separates good lav, tub or shower faucets from the not-so-good is the material they're made of. Start by checking out the body, which encompasses the spout and controls. Solid-brass bodies last longest and require the least care, especially with hard water, which corrodes lesser metals. At $150 or so to start, these faucets also cost the most. If you aren't sure whether a fitting is solid brass, pick it up. It should feel heavier than other units. Often, the box will read "all-brass body" versus "ZMACK" for brass- or chrome-plated fittings. Faucets with die-cast zinc-alloy bodies cost less (typically starting at about $70) and deliver good durability. Zinc is the metal beneath most brass- and chrome-plated fittings. Because zinc corrodes when it contacts water, these faucets must be replaced when the plating wears off. Stay away from low-end faucets with plastic bodies. Though their $50 entry price might be appealing, plastic simply doesn't hold up. Finish is another crucial choice that determines not only how a faucet looks but also how easy it is to maintain. An electroplated chrome finish on a brass or zinc faucet looks good and lasts. If you opt for the warmth of natural brass, you'll avoid frequent cleanings with one of the proprietary lifetime finishes that block out oxidation. Examples of these finishes include Delta Brilliance, Moen LifeShine and Jado Diamond. Pewter, nickel and satin finishes are also easy to maintain. Their muted tones hide water spots, scratches and fingerprints. They also match door and cabinet handles more easily than brass. Chrome and combination chrome-and-brass finishes are popular for baths but require frequent cleaning to maintain their shine. With a spectrum of colors available, going with painted or enamel finishes is the easiest way to individualize a faucet and coordinate it with the rest of the bath. But because most of these finishes aren't bonded to the metal like plating, they chip and scratch relatively easily. Save them for less-used powder rooms and guest baths. More on reddit.com

This is absolutely true, even for water heaters. The plumbing supply houses can give sticker shock on their higher end stuff, so don't expect them to compare to Home Depot prices.. Usually this high end stuff is solid brass and overall better quality. More on reddit.com