There are three types of approaches to pentesting:
Black-box pentesting follows non-deterministic approach of testing
You will be given just a company name
It is like hacking with the knowledge of an outside attacker
There is no need of any prior knowledge of the system
It is time consuming
White-box pentesting follows deterministic approach of testing
You will be given complete knowledge of the infrastructure that needs to be tested
This is like working as a malicious employee who has ample knowledge of the company's infrastructure
You will be provided information on the company's infrastructure, network type, company's policies, do's and don'ts, the IP address, and the IPS/IDS firewall
Gray-box pentesting follows hybrid approach of black and white box testing
The tester usually has limited information on the target network/system that is provided by the client to lower costs and decrease trial and error on the part of the pentester
It performs the security assessment and testing internally