As there is no standard definition of "tightly/loosely coupled", it would be easy to argue that both are tightly coupled, and it would be easy to argue that both are loosely coupled. I'd say that SOAP is more tightly coupled than REST because it specifies the data types to be used, whereas REST does not. That makes it a bit harder (but by no means impossible) to change the implementation without also changing the interface.
I’ve looked at a lot of different solutions, and in my humble opinion Aspose is the way to go. Here’s the link: http://aspose.com
subject: SOAP and REST tightly and loosely coupled