It’s time to become a power user- professionals deserve the Mac Pro.
For build-to-order configurations, please visit B&H Photo Video or MacMall.
The entry level model has less RAM (6GB vs. 12GB) and a slower processor (quad-core vs. 12-core) than the second model. If you're the type of professional that needs the power and configuration options available with a Mac Pro, it makes sense to get the best machine you can afford.
And remember, the best way to increase performance from a new Mac purchase while minimizing investment is to max out the RAM. Check out Apple Sliced Memory
to see the many Mac Pro memory upgrade options.