https://info.kepware.com/blog/kepserverex-thingworx-integration-furthers-industrial-iot - Good page for seeing major difference between the two option.Also stated clearly when to choose IOT gateway and when to choose Native interface .
Regarding licensing what specific question do you have ? Can you please state it clearly .
I notice that IOT Gateway have three purchasing options, and IOT gateway is not included in Manufacturing Suite license. That's say if I got a kepware driver license, I need a extra license for IOT Gateway plug-in. Am I right?
And I can not find any license information for native interface. Is it free for use?