When you are selling a product to a customer, you will have to understand the characteristics of the customer. This is especially true if your product solves the problems of both Enterprises and Startups. Both are unique in the way they buy products. Enterprises have a process in place and hence you need to be very very patient(sometimes, it may take an year for an Enterprise to decide to go with your product). Startups are more willing to experiment and will try out your product more willingly if they think that will help them gain an advantage. The selling points are also different. For Enterprises, you have to be able to convince them that your product is very stable and has already been tested in a production environment. They will give more weightage to existing customer references. Startups are more interested in the feature set. They want the latest bleeding edge feature set which will help them in getting an advantage over the competition.
Based on my experiences, I have listed down the happy and sad characteristics of Enterprise and Startup customers.
So, to put it in a nutshell, Startups decide fast and are willing to take the risk with you, whereas Enterprises are more slow in decision making, but once they decide, they stick with you and pay well.