A level computer scienceWatch
Generally speaking, Information Technology is focused on areas such as IT management, project management, software applications (e.g. Microsoft Office/Access/etc.), social media, usage of information/data in business, and various legal, ethical and professional issues related to IT
Computer Science tends to be a lot more technical - The focus tends to be on programming, algorithms, problem-solving, computational thinking, hardware, networking, and computer science theory.
There's usually some 'cross-over' between the two - for example, IT often covers databases and some web design. Also, Computer Science will usually cover some software project management too; however generally speaking IT is mostly non-technical, whereas Computer Science is a lot more technical.