There are two main differences between a SAR and a FOI request. A subject access request is about your personal data held by any organization, whereas a freedom of information request is a more general one about information held by government organizations.
Example SAR: I'd like to see my credit file.
Example FOI: I'd like to see the report saying that 'project X' was expected to go $2 million over budget and 90% likely to fail.
The subject access request comes from European law: currently the General Data Protection Regulation but was also found in predecessors.
The modern Freedom of Information principles come largely from the USA, as a reaction to the idea that government had become less accountable during the cold war era. As such I think most people would regard the US act as a landmark, although it's not exactly the first.