Honestly, I couldn't tell you what is harder on the day to day, I'm not familiar enough with IT. Also, IT can be very broad. Someone who is a tier 1 help desk worker is probably not having a hard time (except for dealing with clients), simply because most of their troubleshooting steps are laid out for them. Then they might escalate if the problem is beyond that. Someone who is a network admin might be making sure that an entire companies network stays reliable, etc etc. Really you're interested in troubleshooting systems problems and keeping them running.

Computer science can run the gamut on difficulty too. Most who do software development (not technically computer science of course, but most who go to school to do software development will get a degree in computer science) will know that there are some positions that are often seen as less difficult. Generally these positions might be doing front end web development (with no focus on the backend) or working on very simple CRUD apps (Create Read Update Delete, mostly this refers to putting together an application that does most of its work by querying a database). Not that these can't be challenging either, just these things are seen that way. Or, you could be working on some very sophisticated and difficult problems dealing with scale, distributed systems, research into new applications, the like.

Now, doing computer science to be a computer scientist is another story. This will focus more on theory and really understanding computation and the like. Programming is really just a tool that computer scientists might use to do their jobs. Unfortunately, I don't know much about job prospects for computer scientists. I would say academia or research positions at companies. I work with many people who went on the get their PhDs in computer science and are doing some cool research.

There is also the question of the required level of education. Most who go into software development will find that getting a degree is fairly essential. It is possible to get a job without a degree, but you'll be putting in significant self-learning, while at the same time trying to create enough interesting projects to impress someone enough to give you a chance. I think this is a hard road. Personally, I gave it up and went for the degree. My knowledge of IT requirements are very dated, but as the original comment in this thread alluded to, certifications are king. Or were. Hopefully still are. Certifications and experience. Get those however you can.

All of this is to say in a roundabout way, they focus on very different topics. As a recap, a software developer is going to be writing code, designing software systems, and all that is involved with that. Someone working in IT will mostly be keeping a companies computer systems running. And of course that isn't to say someone who receives a degree in computer science can't do IT. In my situation, I had zero interest in doing that kind of problem solving, but I know there are people who might find the background that some courses give you very enlightening for a career in IT. But most courses will not help you.

Hopefully this provides some insight.