What are exact benefits of using R services on Enterprise vs Standard?

I am currently using SQL Server 2016 SP standard edition and want to install R services. In the documentation is said that a stand alone installation is allowed only on Enterprise (Machine Learning Server (Standalone)). Also, I found a post, where the guy is talking that on standard I am not able to use parallel operations and there are memory limitations: Could anyone tell what are the exact memory/processors limitations? I need such details as going to use heavy R calculations and the tests for now show that the implementation in the standard edition is not working as I hoped.