Magento crontab vs Magento Cron (Scheduled Tasks)

I am working with the Magento2 Cron functionality, I have created a cron in the crontab.xml (Every 5 mins) default group

<job instance="NamespaceModuleNameCronServiceOrdersStatusUpdate" method="execute" name="ns_cron_status_update_for_service_orders">
   <config_path>*/5 * * * *</config_path>
        </job>

After that I noticed in admin system->config->system->Cron (Scheduled Tasks). there has some setting (Cron configuration options for group: default).

So when the cron will be execute what is the difference of the both.

Also I’ve created a command line for my cronfile, and added that into Magento crontab as follows

* */2 * * * php /var/www/html/bin/magento  service-order:status-update
#~ MAGENTO START 69dd2b02e1f3a65918182048ea4e29979a849d8942e8f53ed20a4bf10e529b36
#* * * * * /usr/bin/php /var/www/html/bin/magento cron:run 2>&1 | grep -v "Ran jobs by schedule" >> /var/www/html/var/log/cron/magento.cron.log
#* * * * * /usr/bin/php /var/www/html/update/cron.php >> /var/www/html/var/log/cron/update.cron.log
#* * * * * /usr/bin/php /var/www/html/bin/magento setup:cron:run >> /var/www/html/var/log/cron/setup.cron.log
#~ MAGENTO END 69dd2b02e1f3a65918182048ea4e29979a849d8942e8f53ed20a4bf10e529b36

If i am adding the my cron in the crontab, do i need to keep that cron in crontab.xml ?