Open data is the low hanging fruit within Public data

Public data is all the data that is publicly available for everyone to make use for any purposes they wish to use it. And Open data is the subset of Public data. Open data is well-defined, maintained, generally more reliable, and there is some sense of assurance that there will be continuous availability of data as the data and the related documentations, APIs, access points, portals, etc., are  made available by the generator (source institution) or by authorized data aggregator organization. In this sense, from my point of view open data is the low hanging fruit within Public data. Open data is a subset of public data.