It = (THE Pro version + mobile) - (remote database connectivity + enterprise features). It even includes the command-line compiler + lib source, which starter did not. So no real limits in terms of capabilities of the product, mainly limits that relates to license and usage. When you are required to upgrade to a paid version of say pro, the major changes are the license restrictions being lifted. Good move for the community as a whole I think, like you said to get an idea of what it can do with all the features developers come to expect.
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