Are wholesale buyers and retail customers really different? Frankly, there are two answers to this question: yes and no. Yes, because they are different from buyers and those selling to buyers' point of view and no, because principles that apply are same for both types of buying.There is only one real difference, aside that one buys at wholesale prices and other at retail prices, and that is that wholesale buyers are looking for a selection of items to fill a space or their customers' needs, while retail buyers are looking for one item to fill a space or need. When there isn't any space that needs filling either now or in future, customer won't be interested in what you have for sale, which means zero sales.
Both wholesale and retail buyers are looking for things that can be either complementary or in contrast to what are doing or they already have. It is rather a combination of two (contrast/complementary or complementary/contrast) than a case of complementary or contrast.
Contrast/complementary means it's different to what they are doing or they have, but will fit in with other things, while complementary/contrast means it's like what they are doing or already have and yet it's different. If there is a high contrast and it doesn't fit in or if it's exactly what they have, they most likely won't buy.
There are two things you will have to do to determine if buyers are in a contrast/complementary or complementary/contrast buying situations. First of all, listen to what customers say and think about these two things: why they are asking question that way and where they got idea that generated question. This is called "listening between lines". Often, through their questions, customers will tell you what they are looking for. In case they don't, ask them yourself. It helps you by showing interest in what they are doing and their answers will help you make your presentation. Plus, since you know that they are looking for something to fill a need or hole, it becomes much easier to relate to customers' needs.