Setting permissions for folder and file access in Linux

[honey bee]

Hello,

What's the difference between chmod and setfacl commands?.If i have three folders:

Folder1, Folder2, Folder3

All of them belong to same group and their owners are user1, user2 and user3 respectively.All these folders have 2 sub-folders.

Now, i have another system user "user4", i want to give this user access rights for only Folder1 and on one of the sub-folder of Folder2.How i'll do that in linux?

[honey bee]

Found a solution:
To set user permission for a particular folder we use the command "setfacl":

setfacl -m user:username:rwx foldername

, where "rwx" is for read, write and execute, similarly for read only "r--", write only "-w-", execute only "--x".