TOPIC: Difference between Release Planning meeting and Sprint Planning event

yes i understand that they are two separate activities.
But I realized that they are pretty similar in terms of objective : review goal, present user stories, perform user story estimation for the purpose of creating product backlog.
so I am confused, what is the benefit of having two of such meetings?

Within the Sprint Planning meeting the (single) scrum team will plan the work of the next sprint. (to delivery of PSPI)
Within the release planning meeting (multiple) scrum team(s) will plan the work of all next sprints till the release of the product (to deliver a product increment/release)

is it something related to having multiple teams ? what if we have only single scrum team do we still need release planning ? and if we do ,does it mean we will estimate the user stories twice ?

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.