Sales will tell you they’re the same thing.
Marketing is understanding your product and market needs and developing strategies to make your product viable for the market. It also means identifying new consumer markets for your product, or using research to better determine what enhancements are needed to your products or product line to meet the needs of consumers of your product.
Advertising takes the strategy developed by marketing and creates messaging around that strategy, determines what sort of placement of that message will be most effective to bring awareness and need to potential consumers of the product.
Sales is the relationship with the consumer.
It’s an isosceles triangle
Marketing = “think”
Advertising = “communicate”
Sales = “act”
If do any of the three without the other two, you don’t get optimal results. Organizations get in trouble when sales think they know what needs to be done based on ground experience, but often they don’t understand what the real issues are because they are too close to making the sale. In some industries they can reside in one area, but usually not.