How do I secure my SaaS startup?

What are some differences between a SaaS startup and any other kind of startup?

• Couldn't any web application that could be monetized be considered a SaaS? What are the differences between a SaaS startup and any other one: social network, e-commerce, ads, etc.? Aren't all "softwares that are used like services, and are paid by someone"? What could not be considered a SaaS?

• Answer:

  SaaS usually implies that there is an immediate focus on revenue, even if the startup is willing to take a loss at first, before they reach scale. Other startup models include focusing solely on technology or user adoption and engagement, with no revenue model in sight.  The companies are basically hoping for a valuable exit opportunity, or to somehow figure out a revenue source later on (and becoming SaaS).  It's no less of a valid strategy, but is more of a "go big or go home" plan, and has a much higher failure rate (though its successes are often enormous.) Someone with more experience investing in startups could probably answer with better figures, but my feeling is that the return on investment on a startup with a solid SaaS business plan in place is higher than one without.