Pyramids, MLM, Network Marketing... What is the difference and why would one choose one over the other?

People have given a bad name to Pyramids. In my opinion they have been given new names such as MLM, Network Marketing and even some Direct Sell opportunities, when you really look at it, it's structure will resemble a Pyramid.

Whatever you are involved in currently whether online or off, whether you offer products or a service, there is some type of structure involved either a education followed by certification, license and the customers that you provide your product or service to.

Or some one introduced you and a few others to a product/service that came with the opportunity for you to profit in some way by sharing it with others. Also those that you share this product/service with are given the same opportunity if they also share.

Is this apart of marketing and an incentive for the word of mouth promotion of ones product or service.

As a Stylist/Massage Therapist by trade, one in this profession would give their customers a free or discounted service for referring new customers. As the chain reaction continues of people referring others it becomes a Pyramid with the Stylist at the top reaping the benefits of a money producing client base and customers benefiting from referring others. 

Everyone Wins

So my question is what is the difference in a Pyramid whether online or offline, internet marketing or other, and is it really a bad thing.

Love to here your feedback.

Thanks

Anginetta