This document is signed by both the company and the worker. It has language that is specific to the worker's agreement with the company in regards to the worker's equity and vesting.
This document creates a pool of equity with a particular number of shares backing the pool up. This document is signed by the company and references the Plan document.
This optional document can be used by the company to specify the working relationship between the worker and the company. It can be used for employees, contractors and advisers. It also includes IP protection, confidentiality, and non-compete language. Some companies may not need to use this if they already have an employment agreement in place.