Weekly Reader Question: What’s the difference between a “startup” and a “company”?

I’ve been blown away by the quality of comments on The Startup Foundry, so I’ve decided to start a weekly question that allows us to harness this great community’s insight. If it’s well received, we will make this a weekly occurrence.

What’s the difference between a “startup” and “company”? More specifically, when do you think a startup should start calling itself a company? Should it be profitable? Perhaps it’s more of an art then a science, more qualitative then quantitative?

What do you think? Please sound off in the comments.