The main difference between the REFT (Roll End Front Tuck or Roll End Lock Front mailers) and the REFT with Dust Flaps is the side dust flaps. If your box will be used as the shipping box for your product, dust flaps can prevent dirt and other outside elements from entering your box during transit.
These styles do look different visually since the REFT with Dust Flaps tucks in neatly to the walls of the box, and you can see the side folds. In addition to added product protection, dust flaps offers a great unboxing experience for your customer.
However, the REFT lid without dust flaps runs flush to the sides of the box and covers the side folds, which exposes more cardboard fluting. Make sure you consider this when deciding on the look and feel of your product packaging.