To be pedantic, 1.5e8 carries additional information about accuracy: $150,000,000 ± $5,000,000. By contrast, 1.50e8 would be ten times as accurate, and so on.
On the other hand, if you had said "Pi is 3", you would have been accurate, but not very precise. If you said "Pi is "Pi is 3.14", you would have been so precise that you could have gotten to the moon and back.
Of course, accuracy is hardly relevant here.