I've heard this described as a top-down versus bottom-up approach. The problem with the top-down approach (i.e. I will capture 1% of the market) is that is does

I've heard this described as a top-down versus bottom-up approach. The problem with the top-down approach (i.e. I will capture 1% of the market) is that is doesn't tell us much about how you'll capture this 1%. By going from the bottom-up we can clearly see how you are going to iterate and build your userbase.