Confused on GUIDs and how they work

I have a lookup field called "Sales Contact", but I am confused about the GUID retrieved. When I lookup a record and use the following line:

var sales_contact = Xrm.Page.data.entity.attributes.get("new_sales_contact").getValue()[0].id;

I get the following GUID: {E65BE9EB-2DD5-E211-A2B7-AC162DBE2488}

But the record itself, has the following GUID: {E77E79C1-08DF-E211-A1B5-AC162DBE3FFE}

Am I right in assuming that the first GUID is just to identify the lookup because it doesn't give me the GUID of the actual record. If so how can I get the GUID of the actual record?