How redirect after registration?

You can use register_new_user hook which is the last hook before WordPress perform the redirect to check your email page.

In the callback function you will get user ID, using it get the user data and check if user belongs to specific role.

Example:-

function wpse_228545_register_redirect( $user_id ) {
    $user_data = get_userdata($user_id); //Get the user data
    $roles = !empty($user_data->roles) ? $user_data->roles : array();
    $page_slug = '';

    if ( in_array('employee', $roles) ){
        $page_slug = 'employee';
    } else if ( in_array('employer', $roles) ) {
        $page_slug = 'employer';
    }

    if ( $page_slug ) {
        //You can use get_permalink() and get_page_by_path() 
        //if you have different URL structure Or want to change in future.
        wp_safe_redirect( site_url( $page_slug ) );
        exit;
    }

    return;
}
add_action('register_new_user', 'wpse_228545_register_redirect');