In my opinion, the Sprint planning covers the horizon of typically two to four weeks out. In release planning, the team can choose between "ideal days" and "story points."
Sprint planning is an event in scrum that kicks off the sprint. The purpose of sprint planning is to define what can be delivered in the sprint and how that work will be achieved. Sprint planning is done in collaboration with the whole scrum team.
Release planning is longer-term planning that enables us to answer questions like “When will we be done?” or “Which features can I get by the end of the year?” or “How much will this cost?” Release planning must balance customer value and overall quality against the constraints of scope, schedule, and budget.