Hi,
can we create Different dashboards for student and teacher ?
What is a 'teacher'? What is a 'student'?
As far as Moodle is concerned, these are roles that only really apply within an individual course - at the site level, where the dashboards are concerned, they are only 'users'.
But to give a (hopefully) slightly more helpful answer, Moodle does not give the option of specifying a different default dashboard layout for different users. However, users are free to customise their own dashboard, once they have logged in.
This is, of course, something that could be developed for an individual Moodle site, which is why I assume you've posted it in the developer forum, but it would probably require a reasonable amount of changes to the core Moodle code (always a bad idea from a maintenance perspective).
The simplest way, without custom development, is to change the'View Block' permissions for certain roles, for the blocks you want to display or hide.
In other words, this with the Teacher role would see some blocks but not others, and those with the Student role would see some blocks but not others. See https://moodle.org/mod/forum/discuss.php?d=318747#p1278630 for more information.
You can do this with any block in Moodle, but from v2.8 onwards, it appears that the 'Assign Roles' link has gone for blocks on the Dashboard page - but if you have access to the backend database, you can trick Moodle if you know the contextid number of the block. See https://moodle.org/mod/forum/discuss.php?d=318747#p1294163 for more information and instructions.