I've found the solution.
I've accessed the liferay services com.liferay.portal.service.UserGroupService from the template and then used it.
1
2#set ($GroupAdministratorName = "Administrators")
3
4#set($userGroupService = $serviceLocator.findService("com.liferay.portal.service.UserGroupService"))
5#set($userGroups = $userGroupService.getUserUserGroups($user_id))
6#set ($isAdministrator = false)
7#foreach ($group in $userGroups)
8 #if ($GroupAdministratorName == $group.getName())
9 #set ($isAdministrator = true)
10 #end
11#end
After this, i just use an if on isAdministrator variable to show what i want.
If someone have a simpler idea i'm here.
Thanks.