Sugar has two primary modules designed to hold a person’s (individuals) data: Leads and Contacts. There are distinctive characteristics for each modules intended use.
A Lead is a person that is a sales prospect. In the Leads stage they have not given an indication to your sales team that they are planning on moving forward with a purchase. Instead, a Lead is in the initial prospecting phase. The Lead may be the primary decision maker, champion, or someone that has reached out to your company regarding your product or service. (You can also think of a lead as a business card that someone gave to you.) If you sell B2B then the Lead will be associated to a company.
Once the Lead is converted to an Account (Company) record they will automatically become a Contact. You can also create more Contacts (people) associated to that one Account. For B2B sales you will likely have many Contacts associated to one Company. As well, you can distinguish appropriately based on job title.
We hope this helps, and please reach out for any questions!