Startups are, by definition, "temporary organization designed to search for a repeatable and scalable business model.” (as reported by Steve Blank).

The main bits differentiating startups from mature companies are:

* Narrow target - startups always start small, focusing on a narrow niche/subset of the industry they aim for. They define the buyer persona, going into as much detail as possible. The focus is crucial for all of the marketing and brand messaging, as well as avoiding ubiquity in their product.

* Agility - startups are flexible. Processes are available, but just loosely followed. During the first 3-4 years, processes are aligned to the process of finding a product-market fit and the available staff at hand. People often determine the culture, buttom-up.

* Speed of execution - startups must move fast. This is one of their key strengths. Less bureaucracy, fewer processes, rapid release cycles. The senior management team (often the co-founders themselves) are heavily involved in the day-to-day operations, responding to customer requests and even support tickets.

* Team efficiency - each and every team member is absolutely crucial to the success of the organization. Looking for experts comfortable working in fast-paced environments. Juggling on a daily basis. Marketers asked to touch code here and there, helping with product planning or sales.

* Startup spirit - the mindset of a startup is different. Things may change rapidly on a daily basis, or multiple times a day. Everyone fights for survival, growth, beating the competition and stealing market share. It's a small army of sort.