Gold, Silver, Bronze tiers: These badges indiciate the standing of Pololu distributors based on criteria such as frequency of orders and number of items carried. Within each country, gold-tier distributors are listed first, then silver ones, then bronze ones, and then ones without any special standing. Distributors in the same tier are sorted alphabetically. In general, higher-ranked distributors are more likely to have Pololu products you are looking for.
New distributor: This badge designates distributors that have recently started selling Pololu products. New distributors are listed higher than older distributors within the same tier.