All this is my opinion. I see IT as managing and recommending tools that the business uses to function as a business. I see software as just one of those tools. Software development simply develops that software, and generally from a point of view of a closed system product. As a software developer, I would guess the main responsibilities would be to make sure the software functions for whatever business purpose it was created for. But as IT, I try and make all the pieces fit together so that there is a comprehensive picture of how we do business. In my case of the ERP, they are focused on making the product functional at a basic level, but completely miss other business needs, such as security, even though the best place for security measures are at that same software level.
It's like software developers are a car manufacturer, and IT is the transportation planner. You CAN make a car without regards to what kind of road it will be driven on, or if there are any relevant laws that should be part of the original design. But that would likely be an inferior product to something that we designed from the ground up to not only get you from point A to point B (the actual purpose of a car), but to also incorporate things like safety features, or navigation, or whatever so that the overall experience of the user was more than the basic functionality of the actual transportation.
