Not really, in most cases you can use either one. The slight difference there is, can be described like this: "suuri" is used for either abstract or concrete things, while "iso" is mostly reserved for concrete things. For example, "iso mies" means physically big (or adult) man, while "suuri mies" could mean either a physically large man or a great man (like a historical person, or an important man in the society, or some such), depending on the context.
Even this slight difference in usage is disappearing nowadays, as "iso" is spreading to areas that formerly were reserved for only "suuri". In everyday usage and spoken language "iso" might be a bit more frequent.
Source: https://www.kielikello.fi/-/suurella-sydamella-tai-isolla (an article by Riina Klemettinen on the subject, in Finnish).