Re: What's the difference of functional and scaling of community version and comercial version
In terms of functionality, Magento Commerce (EE) includes lots of features that Magento Open Source (CE) does not. In order to get EE functionality with CE, you need to buy extensions, sign up for 3rd party services, write your own custom-coded solutions, or a mix of the above. Examples of features included with EE as part of a commercial Magento Commerce license include:
It can be tough to keep tabs on this, because Magento hasn't historically kept a good list publicly available, which seems like a shame because it would be helpful to show merchants all of the extra value they could potentially get from Magento Commerce.
In terms of scalability, at JetRails, we can autoscale for Magento Open Source and for Magento Commerce (both horizontally and vertically). We have not specifically run into a merchant that's outgrown Magento Open Source from a scalabilty perspective, and we host some huge merchants on Magento Open Source. However, Magento Commerce does offer some scalability benefits - more specifically, database sharding.
I'll also add that Magento has created an easier path to upgrade from M2 Open Source to M2 Commerce which I recently became aware of. I don't know anyone that's used this yet, but, if you went Open Source and eventually wanted to upgrade to Commerce, it's not supposed to be as hard to upgrade as it would have been with older versions of Magento. See: https://devdocs.magento.com/guides/v2.3/comp-mgr/upgrader/ce-ee-upgrade-start.html. I imagine that there would be some debugging during user-acceptance-testing when using this method to upgrade from M2 CE to M2 EE, but you're not supposed to have to start over completely, which is a big plus in my book.