Can I import users to another site according to user roles?

Yes, you can import users to another site according to user roles. To import users from site 1 to site 2 at first you need to export users from site 1.

If you are using a membership plugin then you have to select the proper metadata in the box while exporting the users from site 1 (shown in the screenshot)

Then you can simply import the users in site 2 by choosing the database file you just exported from site 1.