The exact sequence in which jobs are executed will depend on the implementation of your systems' crond.
What is your OS?
If you have cronjob in a crontab:

 Job 1
 Job 2
 Job 3

In Debian Job1 will start, without waiting to finish Job 2, etc. <br> In Debian and Ubuntu derivatives it is top-bottom <br>
In FreeBSD it is bottom-top <br>

If your cronjobs are in /etc/cron.hourly(or daily/monthly/weekly) - then the script that runs them does it sequently, not in paralel. (a script loops though them and waits for each to finish) <br>



**EDIT**
Add two different cronjobs (here I assume you have syslog configured) <br>
`* * * * * ls /etc/` <br>
`* * * * * echo "whatever` <br>
``tail -f /var/log/cron``