What is functional and behavioral model in software engineering?

Functional model: functional model is a part of the software engineering where the team has to gather the requirements according to the specifications. The moto of the team is to check wether the requirements are fulfilled for the prerequisite specifications. The job of the team in this stage is bit challenging as the requirements should meet the specifications behavioural model: it is also a part of se process where the concentrates on design than the requirement gathering like the prog language suitable for the code,number of lines the code takes,number of bugs per 1000 lines of code etc. Here the work of the team will be little risky as the requirements are already gathered