Basically, both are software systems that are based on data and algorithms.
This is a very vague question. However, I will try to make sense of it. Considering rules of logic as well as your statement that both entities are "software systems that are based on data and algorithms", it appears that data products are intelligent systems and intelligent systems are, to some degree, data products. Therefore, it can be argued that the difference between the terms "data products" and "intelligent systems" is purely in the focus (source of information or purpose of system dimensions) of each type of systems (data vs. intelligence/algorithms).