Complex sentence: The only difference between Price Less Foods and Price Less IGA is that "Foods" don't sell IGA brand products like "IGA" does, they sell Best Choice and Always Save brands and they both also sell top national brands.
Split into simpler sentences: The only difference between Price Less Foods and Price Less IGA is that "Foods" does not sell IGA brand products. They sell Best Choice and Always Save brands and they both also sell top national brands.