Gus ran a high-tech meth superlab under a laundry factory. Walt on the other hand runs an operation that had to move form house to house, and never really had Gus' level of resources. The purity of the dope also fell from 96% to 60% after Walt left, which speaks about the low quality of the operation that Walt left after retiring.
Lol, the european distributors that Walt benefitted from were also connected with Gus. Walt's so-called "Czech Empire" is nothing to brag about when you're being compared to Gustavo Fring.