A record type is a label on a record that tells Salesforce which picklist values, page layout and business process to show for that record. Think of one paper form printed in two versions: the questions that matter stay, the ones that do not get dropped, and everything still goes into the same filing cabinet.
That matters the day sales asks why partners and direct customers see the same twenty fields. With record types in Salesforce you give each group its own version of the Account form without building a second object. By the end you will know what a record type controls, how to create one, how to change it on existing records and how to deploy it to production.
The diagram shows the one idea to hold on to: the data stays in one object. The record type only changes what the user sees and can pick, and profiles or permission sets decide which record types a user may choose.