Is Foreign key required in Star or Snow flake schema?

I am currently working in creating Data ware house,i need to know if Foreign keys are required to create a star or snow flake schema ?

If there would not be any foreign key constraints… how would i differentiate btw star and snowflake schema ?

i read this but i still dont get it [Is it good practice to have foreign keys in a datawarehouse (relationships)?]

(database - Is it good practice to have foreign keys in a datawarehouse (relationships)? - Stack Overflow)

if no Fk constraints how would you differerentiate star and snow flake schema ?